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1

Degradation of Methylene Blue Using Biologically Synthesized Silver Nanoparticles  

PubMed Central

Nowadays plant mediated synthesis of nanoparticles has great interest and achievement due to its eco-benign and low time consuming properties. In this study silver nanoparticles were successfully synthesized by using Morinda tinctoria leaf extract under different pH. The aqueous leaf extract was added to silver nitrate solution; the color of the reaction medium was changed from pale yellow to brown and that indicates reduction of silver ions to silver nanoparticles. Thus synthesized silver nanoparticles were characterized by UV-Vis spectrophotometer. Dispersity and morphology was characterized by scanning electron microscope (SEM); crystalline nature and purity of synthesized silver nanoparticles were revealed by X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). FTIR spectrum was examined to identify the effective functional molecules responsible for the reduction and stabilization of silver nanoparticles synthesized by leaf extract. The photocatalytic activity of the synthesized silver nanoparticles was examined by degradation of methylene blue under sunlight irradiation. Green synthesized silver nanoparticles were effectively degrading the dye nearly 95% at 72?h of exposure time. PMID:24772055

Vanaja, M.; Paulkumar, K.; Baburaja, M.; Rajeshkumar, S.; Gnanajobitha, G.; Malarkodi, C.; Sivakavinesan, M.; Annadurai, G.

2014-01-01

2

Cytotoxicity and antimicrobial activities of green synthesized silver nanoparticles.  

PubMed

Bio-inspired silver nanoparticles are synthesized using Malus domestica (apple) extract. Polyphenols present in the apple extract act as a reducing and capping agent to produce the silver nanoparticles. UV-Visible analysis shows the surface plasmon resonance (SPR) absorption at 420 nm. The FTIR analysis was used to identify the functional groups responsible for the bio-reduction of silver ion. The XRD and HRTEM images confirm the formation of silver nanoparticles. The minimal inhibitory concentration (MIC) of silver nanoparticles was recorded against most of the bacteria and fungus. Further, MCF-7 human breast adenocarcinoma cancer cell line was employed to observe the efficacy of cancer cell killing. PMID:24583606

Lokina, S; Stephen, A; Kaviyarasan, V; Arulvasu, C; Narayanan, V

2014-04-01

3

Antibacterial and catalytic activities of green synthesized silver nanoparticles  

NASA Astrophysics Data System (ADS)

The aqueous beetroot extract was used as reducing agent for silver nanoparticles synthesis. The synthesized nanoparticles were characterized using UV-visible spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The surface plasmon resonance peak of synthesized nanoparticles was observed at 438 nm. As the concentration of beetroot extract increases, absorption spectra shows blue shift with decreasing particle size. The prepared silver nanoparticles were well dispersed, spherical in shape with the average particle size of 15 nm. The prepared silver nanoparticles are effective in inhibiting the growth of both gram positive and gram negative bacteria. The prepared silver nanoparticles reveal faster catalytic activity. This natural method for synthesis of silver nanoparticles offers a valuable contribution in the area of green synthesis and nanotechnology avoiding the presence of hazardous and toxic solvents and waste.

Bindhu, M. R.; Umadevi, M.

2015-01-01

4

Catalytically and biologically active silver nanoparticles synthesized using essential oil  

NASA Astrophysics Data System (ADS)

There are numerous reports on phytosynthesis of silver nanoparticles and various phytochemicals are involved in the reduction and stabilization. Pure explicit phytosynthetic protocol for catalytically and biologically active silver nanoparticles is of importance as it is an environmentally benign green method. This paper reports the use of essential oil of Myristica fragrans enriched in terpenes and phenyl propenes in the reduction and stabilization. FTIR spectra of the essential oil and the synthesized biogenic silver nanoparticles are in accordance with the GC-MS spectral analysis reports. Nanosilver is initially characterized by an intense SPR band around 420 nm, followed by XRD and TEM analysis revealing the formation of 12-26 nm sized, highly pure, crystalline silver nanoparticles. Excellent catalytic and bioactive potential of the silver nanoparticles is due to the surface modification. The chemocatalytic potential of nanosilver is exhibited by the rapid reduction of the organic pollutant, para nitro phenol and by the degradation of the thiazine dye, methylene blue. Significant antibacterial activity of the silver colloid against Gram positive, Staphylococcus aureus (inhibition zone - 12 mm) and Gram negative, Escherichia coli (inhibition zone - 14 mm) is demonstrated by Agar-well diffusion method. Strong antioxidant activity of the biogenic silver nanoparticles is depicted through NO scavenging, hydrogen peroxide scavenging, reducing power, DPPH and total antioxidant activity assays.

Vilas, Vidya; Philip, Daizy; Mathew, Joseph

2014-11-01

5

Catalytically and biologically active silver nanoparticles synthesized using essential oil.  

PubMed

There are numerous reports on phytosynthesis of silver nanoparticles and various phytochemicals are involved in the reduction and stabilization. Pure explicit phytosynthetic protocol for catalytically and biologically active silver nanoparticles is of importance as it is an environmentally benign green method. This paper reports the use of essential oil of Myristica fragrans enriched in terpenes and phenyl propenes in the reduction and stabilization. FTIR spectra of the essential oil and the synthesized biogenic silver nanoparticles are in accordance with the GC-MS spectral analysis reports. Nanosilver is initially characterized by an intense SPR band around 420 nm, followed by XRD and TEM analysis revealing the formation of 12-26 nm sized, highly pure, crystalline silver nanoparticles. Excellent catalytic and bioactive potential of the silver nanoparticles is due to the surface modification. The chemocatalytic potential of nanosilver is exhibited by the rapid reduction of the organic pollutant, para nitro phenol and by the degradation of the thiazine dye, methylene blue. Significant antibacterial activity of the silver colloid against Gram positive, Staphylococcus aureus (inhibition zone--12 mm) and Gram negative, Escherichia coli (inhibition zone--14 mm) is demonstrated by Agar-well diffusion method. Strong antioxidant activity of the biogenic silver nanoparticles is depicted through NO scavenging, hydrogen peroxide scavenging, reducing power, DPPH and total antioxidant activity assays. PMID:24956490

Vilas, Vidya; Philip, Daizy; Mathew, Joseph

2014-11-11

6

Characterization and Biocompatibility of ``Green'' Synthesized Silver Nanoparticles  

NASA Astrophysics Data System (ADS)

With ever increasing emphasis on nanotechnology, silver nanoparticle are being considered for many antimicrobial needs ranging from catheter coatings, to burn wound bandages. Current synthesis methods for creating silver nanoparticles typically call for potentially hazardous chemicals, extreme heat, and produce environmentally dangerous byproducts. As a culture intent on reducing our carbon footprint on the earth, societies' focus has turned to ``green'' production capabilities. Therefore, if nanotechnology is to continue to grow at its current rate it is essential that novel ``green'' synthesis of nanoparticles becomes a reality. Furthermore, with the current and near-future applications of silver nanoparticles in biological systems it is imperative to fully analyze the potential toxic effects of these nanoparticles. In this study we have shown that by reducing silver nitrate in solutions of tea extract or epinephrine of varying concentrations spherical silver nanoparticle are formed. Furthermore, evaluation of mitochondrial function (MTS) and membrane integrity (LDH) in alveolar rat macrophages and human keratinocytes showed that these ``green'' synthesized silver nanoparticles were nontoxic.

Moulton, Michael; Kunzelman, Samantha; Braydich-Stolle, Laura; Nadagouda, M.; Varma, R.; Hussain, Saber

2008-10-01

7

Evaluation of green synthesized silver nanoparticles against parasites  

Microsoft Academic Search

Green nanoparticle synthesis has been achieved using environmentally acceptable plant extract and eco-friendly reducing and\\u000a capping agents. The present study was based on assessments of the antiparasitic activities to determine the efficacies of\\u000a synthesized silver nanoparticles (AgNPs) using aqueous leaf extract of Mimosa pudica Gaertn (Mimosaceae) against the larvae of malaria vector, Anopheles subpictus Grassi, filariasis vector Culex quinquefasciatus Say

Sampath Marimuthu; Abdul Abdul Rahuman; Govindasamy Rajakumar; Thirunavukkarasu Santhoshkumar; Arivarasan Vishnu Kirthi; Chidambaram Jayaseelan; Asokan Bagavan; Abdul Abduz Zahir; Gandhi Elango; Chinnaperumal Kamaraj

2011-01-01

8

Antibacterial activity of silver nanoparticles synthesized from serine.  

PubMed

Silver nanoparticles (Ag NPs) were synthesized by a simple microwave irradiation method using polyvinyl pyrrolidone (PVP) as a capping agent and serine as a reducing agent. UV-Visible spectra were used to confirm the formation of Ag NPs by observing the surface plasmon resonance (SPR) band at 443nm. The emission spectrum of Ag NPs showed an emission band at 484nm. In the presence of microwave radiation, serine acts as a reducing agent, which was confirmed by Fourier transformed infrared (FT-IR) spectrum. High-resolution transmission electron microscopy (HR-TEM) and high-resolution scanning electron microscopy (HR-SEM) were used to investigate the morphology of the synthesized sample. These images showed the sphere-like morphology. The elemental composition of the sample was determined by the energy dispersive X-ray analysis (EDX). Selected area electron diffraction (SAED) was used to find the crystalline nature of the Ag NPs. The electrochemical behavior of the synthesized Ag NPs was analyzed by the cyclic voltammetry (CV). Antibacterial experiments showed that the prepared Ag NPs showed relatively similar antibacterial activities, when compared with AgNO3 against Gram-positive and Gram-negative bacteria. PMID:25686955

Jayaprakash, N; Judith Vijaya, J; John Kennedy, L; Priadharsini, K; Palani, P

2015-04-01

9

Antibacterial applications of silver nanoparticles synthesized by aqueous extract of Azadirachta indica (Neem) leaves.  

PubMed

Silver nanoparticles are known to have bactericidal effects. A new generation of dressings incorporating antimicrobial agents like silver nanoparticles is being formulated to reduce or prevent infections. The particles can be incorporated in materials and cloth rendering them sterile. Recently, it was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. Apart from being environmentally friendly process, use of Neem leaves extract might add synergistic antibacterial effect of Neem leaves to the biosynthesized nanoparticles. With this hypothesis the biosynthetic production of silver nanoparticles by aqueous extract of Neem leaves and its bactericidal effect in cotton cloth against E. Coli were studied in this work. Silver nanoparticles were synthesized by short-term (1 day) and long-term (21 days) interaction of Neem extract (20% w/v) and 0.01 M AgNO3 solution in 1:4 mixing ratio. The synthesized particles were characterized by UV visible spectroscopy, transmission electron microscopy, and incorporated into cotton disks by (i) centrifuging the disks with liquid broth containing nanoparticles, (ii) in-situ coating process during synthesis, and (iii) coating with dried and purified nanoparticles. The antibacterial property of the nanoparticles coated cotton disks was studied by disk diffusion method. The effect of consecutive washing of the coated disks with distilled water on antibacterial property was also investigated. This work demonstrates the possible use of biologically synthesized silver nanoparticles by its incorporation in cloths leading them to sterilization. PMID:20055111

Tripathi, A; Chandrasekaran, N; Raichur, A M; Mukherjee, A

2009-02-01

10

Oxidative stress mediated cytotoxicity of biologically synthesized silver nanoparticles in human lung epithelial adenocarcinoma cell line  

PubMed Central

The goal of the present study was to investigate the toxicity of biologically prepared small size of silver nanoparticles in human lung epithelial adenocarcinoma cells A549. Herein, we describe a facile method for the synthesis of silver nanoparticles by treating the supernatant from a culture of Escherichia coli with silver nitrate. The formation of silver nanoparticles was characterized using various analytical techniques. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction analysis show a characteristic strong resonance centered at 420 nm and a single crystalline nature, respectively. Fourier transform infrared spectroscopy confirmed the possible bio-molecules responsible for the reduction of silver from silver nitrate into nanoparticles. The particle size analyzer and transmission electron microscopy results suggest that silver nanoparticles are spherical in shape with an average diameter of 15 nm. The results derived from in vitro studies showed a concentration-dependent decrease in cell viability when A549 cells were exposed to silver nanoparticles. This decrease in cell viability corresponded to increased leakage of lactate dehydrogenase (LDH), increased intracellular reactive oxygen species generation (ROS), and decreased mitochondrial transmembrane potential (MTP). Furthermore, uptake and intracellular localization of silver nanoparticles were observed and were accompanied by accumulation of autophagosomes and autolysosomes in A549 cells. The results indicate that silver nanoparticles play a significant role in apoptosis. Interestingly, biologically synthesized silver nanoparticles showed more potent cytotoxicity at the concentrations tested compared to that shown by chemically synthesized silver nanoparticles. Therefore, our results demonstrated that human lung epithelial A549 cells could provide a valuable model to assess the cytotoxicity of silver nanoparticles. PMID:25242904

2014-01-01

11

Oxidative stress mediated cytotoxicity of biologically synthesized silver nanoparticles in human lung epithelial adenocarcinoma cell line  

NASA Astrophysics Data System (ADS)

The goal of the present study was to investigate the toxicity of biologically prepared small size of silver nanoparticles in human lung epithelial adenocarcinoma cells A549. Herein, we describe a facile method for the synthesis of silver nanoparticles by treating the supernatant from a culture of Escherichia coli with silver nitrate . The formation of silver nanoparticles was characterized using various analytical techniques. The results from UV-visible (UV-vis) spectroscopy and X-ray diffraction analysis show a characteristic strong resonance centered at 420 nm and a single crystalline nature, respectively. Fourier transform infrared spectroscopy confirmed the possible bio-molecules responsible for the reduction of silver from silver nitrate into nanoparticles. The particle size analyzer and transmission electron microscopy results suggest that silver nanoparticles are spherical in shape with an average diameter of 15 nm. The results derived from in vitro studies showed a concentration-dependent decrease in cell viability when A549 cells were exposed to silver nanoparticles. This decrease in cell viability corresponded to increased leakage of lactate dehydrogenase (LDH), increased intracellular reactive oxygen species generation (ROS), and decreased mitochondrial transmembrane potential (MTP). Furthermore, uptake and intracellular localization of silver nanoparticles were observed and were accompanied by accumulation of autophagosomes and autolysosomes in A549 cells. The results indicate that silver nanoparticles play a significant role in apoptosis. Interestingly, biologically synthesized silver nanoparticles showed more potent cytotoxicity at the concentrations tested compared to that shown by chemically synthesized silver nanoparticles. Therefore, our results demonstrated that human lung epithelial A549 cells could provide a valuable model to assess the cytotoxicity of silver nanoparticles.

Han, Jae Woong; Gurunathan, Sangiliyandi; Jeong, Jae-Kyo; Choi, Yun-Jung; Kwon, Deug-Nam; Park, Jin-Ki; Kim, Jin-Hoi

2014-09-01

12

Surface segregation of silver nanoparticles in the in-situ synthesized Ag\\/PMMA nanocomposites  

Microsoft Academic Search

Silver nanoparticles were synthesized in-situ, by thermal decomposition of (1,1,1,5,5,5 Hexafluoroacetylacetonato)silver(I), Ag(hfac), precursor at 185 ^oC, in thin films of Poly(methyl methacryalate), PMMA. Rutherford backscattering spectrometry, RBS, was used to observe and quantify the silver distribution along the thickness of the sample. Strong surface segregation of nanoparticles to the polymer surface and substrate was observed in PMMA thin films by

Ranjan D. Deshmukh; Russell J. Composto

2006-01-01

13

Evaluation of antioxidant, antibacterial and cytotoxic effects of green synthesized silver nanoparticles by Piper longum fruit.  

PubMed

Silver nanoparticles synthesized through bio-green method has been reported to have biomedical applications to control pathogenic microbes as it is cost effective compared to commonly used physical and chemical methods. In present study, silver nanoparticles were synthesized using aqueous Piper longum fruit extract (PLFE) and confirmed by UV-visible spectroscopy. The nanoparticles were spherical in shape with an average particle size of 46nm as determined by scanning electronic microscopy (SEM) and dynamic light scattering (DLS) particle size analyzer respectively. FT-IR spectrum revealed the capping of the phytoconstituents, probably polyphenols from P. longum fruit extract and stabilizing the nanoparticles. Further the ferric ion reducing test, confirmed that the capping agents were condensed tannins. The aqueous P. longum fruit extract (PLFE) and the green synthesized silver nanoparticles (PLAgNPs) showed powerful antioxidant properties in in vitro antioxidant assays. The results from the antimicrobial assays suggested that green synthesized silver nanoparticles (PLAgNPs) were more potent against pathogenic bacteria than the P. longum fruit extract (PLFE) alone. The nanoparticles also showed potent cytotoxic effect against MCF-7 breast cancer cell lines with an IC 50 value of 67?g/ml/24h by the MTT assay. These results support the advantages of using bio-green method for synthesizing silver nanoparticles with antioxidant, antimicrobial and cytotoxic activities those are simple and cost effective as well. PMID:24268240

Reddy, N Jayachandra; Nagoor Vali, D; Rani, M; Rani, S Sudha

2014-01-01

14

Spectroscopic analysis of biologically synthesized silver nanoparticles under clinorotation  

NASA Astrophysics Data System (ADS)

Nanoparticles are one of the hot topics of research due to their size dependent optical, electrical and magnetic properties & their anti-bacterial and anti-fungal nature. Synthesis of nano particles can be done by various physical and chemical methods. However, Biosynthesis of nanoparticles is environment friendly, can take place around room temperature, and require little intervention or input of energy. In the present study, the synthesis of silver nanoparticles (AgNPs) using bacteria and the effect of clinorotation on rate of synthesis is discussed. The freshly grown bacterial isolate was inoculated in to 250-ml Erlenmeyer flask containing 50 ml sterile nutrient broth (LB). The cultured flasks were incubated in a shaker at 120 rpm for 24 h at 370C. Culture was centrifuged at 10,000 rpm for 10 min. The supernatant was used for carrying extracellular production of silver nanoparticles by mixing it with 5mM AgNO3 solution. The above solution was clinorotated at 2 rpm for 24 h. The synthesis was carried out at 60oC. Visual observation was conducted periodically to check for the nanoparticles formation in normal gravity as well as under clinorotation. UV-visible spectroscopic analysis showed that rate of synthesis was faster in case of clinorotated sample than control. Further, the results of FTIR and XRD characterization will be discussed.

Jagtap, Sagar; Vidyasagar, Pandit; Ghemud, Vipul; Dixit, Jyotsana

15

Antibacterial activity of biogenic silver nanoparticles synthesized with gum ghatti and gum olibanum: a comparative study.  

PubMed

Presently, silver nanoparticles produced by biological methods have received considerable significance owing to the natural abundance of renewable, cost-effective and biodegradable materials, thus implementing the green chemistry principles. Compared with the nanoparticles synthesized using chemical methods, most biogenic silver nanoparticles are protein capped, which imparts stability and biocompatibility, and enhanced antibacterial activity. In this study, we compared the antibacterial effect of two biogenic silver nanoparticles produced with natural plant gums: gum ghatti and gum olibanum against Gram-negative and Gram-positive bacteria. Bacterial interaction with nanoparticles was probed both in planktonic and biofilm modes of growth; employing solid agar and liquid broth assays for inhibition zone, antibiofilm activity, inhibition of growth kinetics, leakage of intracellular contents, membrane permeabilization and reactive oxygen species production. In addition, cytotoxicity of the biogenic nanoparticles was evaluated in HeLa cells, a human carcinoma cell line. Antibacterial activity and cytotoxicity of the silver nanoparticles synthesized with gum ghatti (Ag NP-GT) was greater than that produced with gum olibanum (Ag NP-OB). This could be attributed to the smaller size (5.7?nm), monodispersity and zeta potential of the Ag NP-GT. The study suggests that Ag NP-GT can be employed as a cytotoxic bactericidal agent, whereas Ag NP-OB (7.5?nm) as a biocompatible bactericidal agent.The Journal of Antibiotics advance online publication, 20 August 2014; doi:10.1038/ja.2014.114. PMID:25138141

Kora, Aruna Jyothi; Sashidhar, Rao Beedu

2014-08-20

16

Size-Controlled and Optical Properties of Monodispersed Silver Nanoparticles Synthesized by the Radiolytic Reduction Method  

PubMed Central

Size-controlled and monodispersed silver nanoparticles were synthesized from an aqueous solution containing silver nitrate as a metal precursor, polyvinyl alcohol as a capping agent, isopropyl alcohol as hydrogen and hydroxyl radical scavengers, and deionized water as a solvent with a simple radiolytic method. The average particle size decreased with an increase in dose due to the domination of nucleation over ion association in the formation of the nanoparticles by gamma reduction. The silver nanoparticles exhibit a very sharp and strong absorption spectrum with the absorption maximum ?max blue shifting with an increased dose, owing to a decrease in particle size. The absorption spectra of silver nanoparticles of various particle sizes were also calculated using a quantum physics treatment and an agreement was obtained with the experimental absorption data. The results suggest that the absorption spectrum of silver nanoparticles possibly derived from the intra-band excitations of conduction electrons from the lowest energy state (n = 5, l = 0) to higher energy states (n ? 6; ?l = 0, ±1; ?s = 0, ±1), allowed by the quantum numbers principle. This demonstrates that the absorption phenomenon of metal nanoparticles based on a quantum physics description could be exploited to be added into the fundamentals of metal nanoparticles and the related fields of nanoscience and nanotechnology. PMID:23579953

Saion, Elias; Gharibshahi, Elham; Naghavi, Kazem

2013-01-01

17

Efficacy of plant-mediated synthesized silver nanoparticles against hematophagous parasites  

Microsoft Academic Search

The purpose of the present study was to investigate the acaricidal and larvicidal activity against the larvae of Haemaphysalis bispinosa Neumann (Acarina: Ixodidae) and larvae of hematophagous fly Hippobosca maculata Leach (Diptera: Hippoboscidae) and against the fourth-instar larvae of malaria vector, Anopheles stephensi Liston, Japanese encephalitis vector, Culex tritaeniorhynchus Giles (Diptera: Culicidae) of synthesized silver nanoparticles (AgNPs) utilizing aqueous leaf

Chidambaram Jayaseelan; Abdul Abdul Rahuman; Govindasamy Rajakumar; Thirunavukkarasu Santhoshkumar; Arivarasan Vishnu Kirthi; Sampath Marimuthu; Asokan Bagavan; Chinnaperumal Kamaraj; Abdul Abduz Zahir; Gandhi Elango; Kanayairam Velayutham; Kokati Venkata Bhaskara Rao; Loganathan Karthik; Sankariah Raveendran

18

Phycosynthesis of silver nanoparticles and photocatalytic degradation of methyl orange dye using silver (Ag) nanoparticles synthesized from Hypnea musciformis (Wulfen) J.V. Lamouroux  

NASA Astrophysics Data System (ADS)

In the present investigation, simple and eco-friendly chemical reaction for the synthesis reported on biological synthesis of nano-sized silver and biosynthesis of silver nanoparticles using Hypnea musciformis at room temperature along with photocatalytic degradation of methyl orange dye. The nanoparticles of silver were formed by the reduction of silver nitrate to aqueous silver metal ions during exposure to the extract of red alga H. musciformis. The optical properties of the obtained silver nanoparticles were characterized by applying UV-visible absorption and room temperature photoluminescence. The X-ray diffraction results revealed that the synthesized silver nanoparticles were in the cubic phase. The existence of functional groups was identified using Fourier transform infrared spectroscopy. The morphology and size of the synthesized particles were studied with atomic force microscope measurements. Photocatalytic degradation of methyl orange was measured spectrophotometrically by using silver as nanocatalyst under visible light illumination. The results revealed that biosynthesized silver nanoparticles using H. musciformis was found to be impressive in degrading methyl orange.

Ganapathy Selvam, G.; Sivakumar, K.

2014-09-01

19

Assessment of growth of silver nanoparticles synthesized from an ethylene glycol-silver nitrate-polyvinylpyrrolidone solution  

NASA Astrophysics Data System (ADS)

The growth of silver nanoparticles synthesized at 27±1 °C from an ethylene glycol-silver nitrate-polyvinylpyrrolidone solution has been assessed using a methodology that combines theoretical calculations based on the Mie Theory with experimental UV/VIS spectra and average particle size determinations from TEM micrographs. A plot of experimental maximum absorbance times bandwidth as a function of the corresponding average particle radius cube gives a curve with two linear portions of significantly different slopes, suggesting that formation of silver particles takes place during two distinct periods. These results and theoretical calculations seem to indicate that particle formation involves a long nucleation-growth period (about 13 h) during which the number of particles increases, followed by growth only, with a constant number of particles. The ratio of theoretical and experimental maximum absorbance indicates that even after 67 h of reaction, only 45% of the initial Ag(I) species has been transformed into silver nanoparticles.

Slistan-Grijalva, A.; Herrera-Urbina, R.; Rivas-Silva, J. F.; Ávalos-Borja, M.; Castillón-Barraza, F. F.; Posada-Amarillas, A.

2005-01-01

20

An Improved Insecticidal Activity of Silver Nanoparticle Synthesized by Using Sargassum muticum.  

PubMed

A highly active silver nanoparticle (SmAgNps) was synthesized in the present study by using Sargassum muticum extract. The instrumentations such as scanning electron microscope (SEM), energy dispersive X-ray (EDAX), and X-ray diffraction (XRD) were used to reveal the nanoparticle morphology and size. The insecticidal activities of SmAgNps against Ergolis merione reveals prominent changes in the protein profile of hemolymph, morphology of hemocytes, and deteriorated midgut inclusions such as lumen, basement membrane, fat body, and gastric caeca. From this study, it was observed that phytochemicals of S. muticum was a prominent precursor for the synthesis of highly active nanoparticles. PMID:25240853

Moorthi, P Vinayaga; Balasubramanian, C; Mohan, S

2015-01-01

21

Surface segregation of silver nanoparticles in the in-situ synthesized Ag/PMMA nanocomposites.  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were synthesized in-situ, by thermal decomposition of (1,1,1,5,5,5 Hexafluoroacetylacetonato)silver(I), Ag(hfac), precursor at 185 ^oC, in thin films of Poly(methyl methacryalate), PMMA. Rutherford backscattering spectrometry, RBS, was used to observe and quantify the silver distribution along the thickness of the sample. Strong surface segregation of nanoparticles to the polymer surface and substrate was observed in PMMA thin films by RBS and also confirmed by cross-sectional transmission electron microscopy (TEM). Surface segregation mechanism has been attributed to simultaneous thermal decomposition and diffusion of precursor to polymer surface and substrate. It has been shown that the particles present near the surface could be initially exposed and then are eventually covered by the polymer leading to particle sinking as observed by TEM. Atomic force microscopy (AFM) showed bigger nanoparticles and wider size distribution on increasing the nanoparticle loading from 5 to 20-wt %. UV/Visible spectroscopy on PMMA/Ag nanocomposite films showed plasmon resonance peaked at 422 nm due to the presence of silver nanoparticles.

Deshmukh, Ranjan D.; Composto, Russell J.

2006-03-01

22

Potential Theranostics Application of Bio-Synthesized Silver Nanoparticles (4-in-1 System)  

PubMed Central

In this report, we have designed a simple and efficient green chemistry approach for the synthesis of colloidal silver nanoparticles (b-AgNPs) that is formed by the reduction of silver nitrate (AgNO3) solution using Olax scandens leaf extract. The colloidal b-AgNPs, characterized by various physico-chemical techniques exhibit multifunctional biological activities (4-in-1 system). Firstly, bio-synthesized silver nanoparticles (b-AgNPs) shows enhanced antibacterial activity compared to chemically synthesize silver nanoparticles (c-AgNPs). Secondly, b-AgNPs show anti-cancer activities to different cancer cells (A549: human lung cancer cell lines, B16: mouse melanoma cell line & MCF7: human breast cancer cells) (anti-cancer). Thirdly, these nanoparticles are biocompatible to rat cardiomyoblast normal cell line (H9C2), human umbilical vein endothelial cells (HUVEC) and Chinese hamster ovary cells (CHO) which indicates the future application of b-AgNPs as drug delivery vehicle. Finally, the bio-synthesized AgNPs show bright red fluorescence inside the cells that could be utilized to detect the localization of drug molecules inside the cancer cells (a diagnostic approach). All results together demonstrate the multifunctional biological activities of bio-synthesized AgNPs (4-in-1 system) that could be applied as (i) anti-bacterial & (ii) anti-cancer agent, (iii) drug delivery vehicle, and (iv) imaging facilitator. To the best of our knowledge, there is not a single report of biosynthesized AgNPs that demonstrates the versatile applications (4-in-1 system) towards various biomedical applications. Additionally, a plausible mechanistic approach has been explored for the synthesis of b-AgNPs and its anti-bacterial as well as anti-cancer activity. We strongly believe that bio-synthesized AgNPs will open a new direction towards various biomedical applications in near future. PMID:24505239

Mukherjee, Sudip; Chowdhury, Debabrata; Kotcherlakota, Rajesh; Patra, Sujata; B, Vinothkumar; Bhadra, Manika Pal; Sreedhar, Bojja; Patra, Chitta Ranjan

2014-01-01

23

Mycosynthesis: antibacterial, antioxidant and antiproliferative activities of silver nanoparticles synthesized from Inonotus obliquus (Chaga mushroom) extract.  

PubMed

In the present study, silver nanoparticles (AgNPs) were rapidly synthesized from silver nitrate solution at room temperature using Inonotus obliquus extract. The mycogenic synthesized AgNPs were characterized by UV-Visible absorption spectroscopy, Fourier transform infrared (FTIR), scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and atomic force microscopy (AFM). SEM revealed mostly spherical nanoparticles ranging from 14.7 to 35.2nm in size. All AgNPs concentrations showed good ABT radical scavenging activity. Further, AgNPs showed effective antibacterial activity against both gram negative and gram positive bacteria and antiproliferative activity toward A549 human lung cancer (CCL-185) and MCF-7 human breast cancer (HTB-22) cell lines. The samples demonstrated considerably high antibacterial, and antiproliferative activities against bacterial strains and cell lines. PMID:24380885

Nagajyothi, P C; Sreekanth, T V M; Lee, Jae-il; Lee, Kap Duk

2014-01-01

24

Characterization of silver nanoparticles synthesized by using marine isolate Streptomyces albidoflavus.  

PubMed

Silver nanoparticles production by the green chemistry approach was investigated using an isolated marine actinomycetes strain. The isolated strain was identified as Streptomyces albidoflavus based on chemotaxonomic and ribotyping properties. The strain revealed production of silver nanoparticles both extracellular and intracellularly. Surface Plasmon Resonance analysis with the function of time revealed that particle synthesis by this strain is reaction time dependent. The produced particles were spherical shaped and monodispersive in nature and showed a single surface plasmon resonance peak at 410 nm. Size distribution histograms indicated production of 10-40- nm-size nanoparticles with a mean size of 14.5 nm. FT-IR spectra of nanopartilces showed N-H, C-H, and C-N stretching vibrations, denoting the presence of amino acid/ peptide compounds on the surface of silver nanoparticles produced by S. albidoflavus. Synthesized nanoparticles revealed a mean negative zeta potential and electrophoretic mobility of -8.5 mV and -0.000066 cm2/Vs, respectively. The nanoparticles produced were proteinaceous compounds as capping agents with -8.5 mV zeta potential and revealed antimicrobial activity against both Gram-negative and -positive bacterial strains. Owing to their small size, these particles have greater impact on industrial application spectra. PMID:22561854

Prakasham, Reddy Shetty; Buddana, Sudheer Kumar; Yannam, Sudheer Kumar; Guntuku, Girija Shankar

2012-05-01

25

Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.  

NASA Astrophysics Data System (ADS)

The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise invitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation.

Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

2015-02-01

26

Antibacterial and cytotoxic potential of silver nanoparticles synthesized using latex of Calotropis gigantea L.  

PubMed

The present study aimed to synthesis silver nanoparticles (AgNPs) in a greener route using aqueous latex extract of Calotropis gigantea L. toward biomedical applications. Initially, synthesis of AgNPs was confirmed through UV-Vis spectroscopy which shows the surface plasmonic resonance peak (SPR) at 420 nm. Fourier transform infrared spectroscopy (FTIR) analysis provides clear evidence that protein fractions present in the latex extract act as reducing and stabilizing bio agents. Energy dispersive X-ray (EDAX) spectroscopy confirms the presence of silver as a major constituent element. X-ray diffractograms displays that the synthesized AgNPs were biphasic crystalline nature. Electron microscopic studies such as Field emission scanning electron microscopic (Fe-SEM) and Transmission electron microscope (TEM) reveals that synthesized AgNPs are spherical in shape with the size range between 5 and 30 nm. Further, crude latex aqueous extract and synthesized AgNPs were evaluated against different bacterial pathogens such as Bacillus cereus, Enterococci sp, Shigella sp, Pseudomonas aeruginosa, Klebsiella pneumonia, Staphylococcus aureus and Escherichia coli. Compared to the crude latex aqueous extract, biosynthesized AgNPs exhibits a remarkable antimicrobial activity. Likewise in vitro anticancer study manifests the cytotoxicity value of synthesized AgNPs against tested HeLa cells. The output of this study clearly suggesting that biosynthesized AgNPs using latex of C. gigantea can be used as promising nanomaterial for therapeutic application in context with nanodrug formulation. PMID:25459618

Rajkuberan, Chandrasekaran; Sudha, Kannaiah; Sathishkumar, Gnanasekar; Sivaramakrishnan, Sivaperumal

2015-02-01

27

Size selective photoluminescence in poly(methyl methacrylate) thin solid films with dispersed silver nanoparticles synthesized by a novel method  

NASA Astrophysics Data System (ADS)

Thin solid films of poly(methyl methacrylate) (PMMA) with dispersed silver nanoparticles, synthesized by a novel reaction route, were cast on suitable substrates for characterizing and studying the photoluminescence (PL) property. The peak position of the PL spectrum was observed to shift towards longer wavelength with increasing excitation wavelength in the range of ˜370-550 nm. The observed effect arises due to the resonance between the luminescence transition and silver plasmon. The PMMA thin films with dispersed silver nanoparticles may be useful for nanophotonic devices.

Basak, Dhrubajyoti; Karan, Santanu; Mallik, Biswanath

2006-03-01

28

Photocatalytic activity of biogenic silver nanoparticles synthesized using yeast (Saccharomyces cerevisiae) extract  

NASA Astrophysics Data System (ADS)

Synthesis of metallic and semiconductor nanoparticles through physical and chemical route is quiet common but biological synthesis procedures are gaining momentum due to their simplicity, cost-effectivity and eco-friendliness. Here, we report green synthesis of silver nanoparticles from aqueous solution of silver salts using yeast (Saccharomyces cerevisiae) extract. The nanoparticles formation was gradually investigated by UV-Vis spectrometer. X-ray diffraction analysis was done to identify different phases of biosynthesized Ag nanoparticles. Transmission electron microscopy was performed to study the particle size and morphology of silver nanoparticles. Fourier transform infrared spectroscopy of the nanoparticles was performed to study the role of biomolecules capped on the surface of Ag nanoparticles during interaction. Photocatalytic activity of these biosynthesized nanoparticles was studied using an organic dye, methylene blue under solar irradiation and these nanoparticles showed efficacy in degrading the dye within a few hours of exposure.

Roy, Kaushik; Sarkar, C. K.; Ghosh, C. K.

2014-12-01

29

Microalgae associated Brevundimonas sp. MSK 4 as the nano particle synthesizing unit to produce antimicrobial silver nanoparticles.  

PubMed

The biosynthesis of silver nanoparticles and its antimicrobial property was studied using bacteria isolated from Spirulina products. Isolated bacteria were identified as Bacillus sp. MSK 1 (JX495945), Staphylococcus sp. MSK 2 (JX495946), Bacillus sp. MSK 3 (JX495947) and Brevundimonas sp. MSK 4 (JX495948). Silver nanoparticles (AgNPs) were synthesized using bacterial culture filtrate with AgNO3. The initial syntheses of Ag nanoparticles were characterized by UV-vis spectrophotometer (by measuring the color change to intense brown). Fourier Transform Infrared Spectroscopy (FTIR) study showed evidence that proteins are possible reducing agents and Energy-dispersive X-ray (EDX) study showing the metal silver as major signal. The structure of AgNPs was determined by Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Synthesized Ag nanoparticles with an average size of 40-65 nm have antimicrobial property against human pathogens like Proteus vulgaris, Salmonella typhi, Vibrio cholera, Streptococcus sp., Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. Among the isolates Brevundimonas sp. MSK 4 alone showed good activity in both synthesis of AgNPs and antimicrobial activity. This work demonstrates the possible use of biological synthesized silver nanoparticles to combat the drug resistant problem. PMID:23711394

Rajamanickam, Karthic; Sudha, S S; Francis, Mebin; Sowmya, T; Rengaramanujam, J; Sivalingam, Periyasamy; Prabakar, Kandasamy

2013-09-01

30

Larvicidal activity of synthesized silver nanoparticles using Eclipta prostrata leaf extract against filariasis and malaria vectors.  

PubMed

Mosquitoes transmit serious human diseases, causing millions of deaths every year. Use of synthetic insecticides to control vector mosquitoes has caused physiological resistance and adverse environmental effects in addition to high operational cost. Insecticides of synthesized natural products for vector control have been a priority in this area. In this study, larvicidal activity of synthesized silver nanoparticles (AgNPs) utilizing aqueous extract from Eclipta prostrata, a member of the Asteraceae was investigated against fourth instar larvae of filariasis vector, Culex quinquefasciatus say and malaria vector, Anopheles subpictus Grassi (Diptera: Culicidae). The synthesized AgNPs characterized by UV-vis spectrum, scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD). SEM analyses of the synthesized AgNPs were clearly distinguishable measured 35-60 nm in size. Larvae were exposed to varying concentrations of aqueous extract of synthesized AgNPs for 24h. The maximum efficacy was observed in crude aqueous, and synthesized AgNPs against C. quinquefasciatus (LC(50)=27.49 and 4.56 mg/L; LC(90)=70.38 and 13.14 mg/L), and against A. subpictus (LC(50)=27.85 and 5.14 mg/L; LC(90)=71.45 and 25.68 mg/L) respectively. The chi-square value were significant at p<0.05 level. These results suggest that the synthesized AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the Culex tritaeniorhynchus and A. subpictus. This method is considered as a new approach to control vectors. Therefore, this study provides first report on the mosquito larvicidal activity of synthesized AgNPs against vectors. PMID:21419749

Rajakumar, G; Abdul Rahuman, A

2011-06-01

31

Synthesis, characterization and biocompatibility of ``green'' synthesized silver nanoparticles using tea polyphenols  

NASA Astrophysics Data System (ADS)

Since ancient times, people have taken advantage of the antimicrobial effects of colloidal silver particles. Aside from the medical prospects, silver nanoparticles are found in a wide range of commercially available consumer products ranging from cosmetics to household cleansers. Current synthetic methods for creating silver nanoparticles typically call for potentially hazardous chemicals, extreme heat, and produce environmentally dangerous byproducts. Therefore, it is essential that novel ``green'' synthesis of nanoparticles becomes a reality, and it is imperative to fully analyze the potential toxic effects of these nanoparticles. In this study, we have shown that by reducing silver nitrate in solutions of tea extract or epicatechin of varying concentrations, spherical silver nanoparticles were formed that had controllable size distributions depending on the concentration of tea extract or epicatechin in the samples. Our ultra-resolution microscopy demonstrated that the nanoparticles were in fact interacting with the keratinocytes. Furthermore, evaluation of mitochondrial function (MTS) to assess cell viability and membrane integrity (LDH) in human keratinocytes showed that the silver nanoparticles were nontoxic. These results demonstrated that these nanoparicles are potentially biocompatible and warrant further evaluation in other biological systems.

Moulton, Michael C.; Braydich-Stolle, Laura K.; NadagoudaPresent Address: Pegasus Technical Services, 46 E. Hollister Street, Cincinnati, 45219, Ohio, Usa., Mallikarjuna N.; Kunzelman, Samantha; Hussain, Saber M.; Varma, Rajender S.

2010-05-01

32

Biological activities of green silver nanoparticles synthesized with Acorous calamus rhizome extract.  

PubMed

Nanomedicine utilize biocompatible nanomaterials for diagnostic and therapeutic purposes. This study reports the synthesis of silver nanoparticles using aqueous rhizome extract of Acorus calamus (ACRE) and evaluation of antioxidant, antibacterial as well as anticancer effects of synthesized A. calamus silver nanoparticles (ACAgNPs). The formation of ACAgNPs was confirmed by UV-visible spectroscopy and their average size was found to be 31.83 nm by DLS particle size analyzer. Scanning electron micrograph (SEM) revealed spherical shape of ACAgNPs and energy dispersive spectroscopy (EDX) data showed the presence of metallic silver. Fourier transform infrared spectroscopy (FTIR) analysis indicated the presence of phenol/alcohol, aromatic amine and carbonyl groups in ACRE that were involved in reduction and capping of nanoparticles. ACRE and ACAgNPs exhibited substantial free radical quenching ability in various in vitro antioxidant assays performed in this study. ACAgNPs also displayed appreciable antibacterial activity against three different pathogenic bacteria and the growth kinetic study with Escherichia coli designated the inhibition of bacterial growth at the log phase. The cytotoxic effect of ACAgNPs was assessed by MTT assay in HeLa and A549 cells. The IC50 value of ACAgNPs respectively after 24 and 48 h was found to be 92.48 and 69.44 ?g/ml in HeLa cells and in A549 cells it was 53.2 and 32.1 ?g/ml. Apoptotic cell death in ACAgNPs treated cells was indicated by acridine orange/ethidium bromide (AO/EB) and annexinV-Cy3 staining techniques. Staining with propidium iodide (PI) and 4', 6-diamidino-2-phenylindole, dihydrochloride (DAPI) also confirmed nuclear changes such as condensation and fragmentation. Further, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay showed distribution of ACAgNPs treated cells in the late apoptotic stage. These findings emphasize that such biocompatible green nanoparticles with multifaceted biological activities may find their applications in the field of nanomedicine. PMID:25147142

Nakkala, Jayachandra Reddy; Mata, Rani; Gupta, Arvind Kumar; Sadras, Sudha Rani

2014-10-01

33

Green Synthesized Silver Nanoparticles Exhibit Reduced Toxicity to Mammalian Cells and Retain Antimicrobial Activity  

EPA Science Inventory

The interest in silver nanoparticles (AgNPs) and silver nanomaterial stems from their antimicrobial properties. AgNPs are being added to clothing, paint, refrigerators, washing machines and a variety of other commercially available items. Recent in vitro and in vivo studies, howe...

34

Study on antibacterial activity of silver nanoparticles synthesized by gamma irradiation method using different stabilizers.  

PubMed

Colloidal solutions of silver nanoparticles (AgNPs) were synthesized by gamma Co-60 irradiation using different stabilizers, namely polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), alginate, and sericin. The particle size measured from TEM images was 4.3, 6.1, 7.6, and 10.2 nm for AgNPs/PVP, AgNPs/PVA, AgNPs/alginate, and AgNPs/sericin, respectively. The influence of different stabilizers on the antibacterial activity of AgNPs was investigated. Results showed that AgNPs/alginate exhibited the highest antibacterial activity against Escherichia coli (E. coli) among the as-synthesized AgNPs. Handwash solution has been prepared using Na lauryl sulfate as surfactant, hydroxyethyl cellulose as binder, and 15 mg/L of AgNPs/alginate as antimicrobial agent. The obtained results on the antibacterial test of handwash for the dilution to 3 mg AgNPs/L showed that the antibacterial efficiency against E. coli was of 74.6%, 89.8%, and 99.0% for the contacted time of 1, 3, and 5 min, respectively. Thus, due to the biocompatibility of alginate extracted from seaweed and highly antimicrobial activity of AgNPs synthesized by gamma Co-60 irradiation, AgNPs/alginate is promising to use as an antimicrobial agent in biomedicine, cosmetic, and in other fields. PMID:24708872

Van Phu, Dang; Quoc, Le Anh; Duy, Nguyen Ngoc; Lan, Nguyen Thi Kim; Du, Bui Duy; Luan, Le Quang; Hien, Nguyen Quoc

2014-01-01

35

Study on antibacterial activity of silver nanoparticles synthesized by gamma irradiation method using different stabilizers  

PubMed Central

Colloidal solutions of silver nanoparticles (AgNPs) were synthesized by gamma Co-60 irradiation using different stabilizers, namely polyvinyl pyrrolidone (PVP), polyvinyl alcohol (PVA), alginate, and sericin. The particle size measured from TEM images was 4.3, 6.1, 7.6, and 10.2 nm for AgNPs/PVP, AgNPs/PVA, AgNPs/alginate, and AgNPs/sericin, respectively. The influence of different stabilizers on the antibacterial activity of AgNPs was investigated. Results showed that AgNPs/alginate exhibited the highest antibacterial activity against Escherichia coli (E. coli) among the as-synthesized AgNPs. Handwash solution has been prepared using Na lauryl sulfate as surfactant, hydroxyethyl cellulose as binder, and 15 mg/L of AgNPs/alginate as antimicrobial agent. The obtained results on the antibacterial test of handwash for the dilution to 3 mg AgNPs/L showed that the antibacterial efficiency against E. coli was of 74.6%, 89.8%, and 99.0% for the contacted time of 1, 3, and 5 min, respectively. Thus, due to the biocompatibility of alginate extracted from seaweed and highly antimicrobial activity of AgNPs synthesized by gamma Co-60 irradiation, AgNPs/alginate is promising to use as an antimicrobial agent in biomedicine, cosmetic, and in other fields. PMID:24708872

2014-01-01

36

Physicochemical characterization of silver nanoparticles synthesize using Aloe Vera (Aloe barbadensis)  

NASA Astrophysics Data System (ADS)

Production of silver nanoparticles (AgNPs) using different biological methods is gaining recognition due to their multiple applications. Although, several physical and chemical methods have been used for the synthesis and stabilizing of AgNPs, yet, a green chemistry method is preferable because it is cost effective and environmentally friendly. The synthesis was done using Aloe Vera (AV) extract because it has chemical compounds such as "Antrokinon" that are known for its antibacterial, antivirus and anticancer properties. We hypothesize that AV extract can produce a stable nanoparticles within the 100 nm range and be biologically active. The biological compounds were extracted from AV skin with water and ethanol which was used as the reduction agent for the synthesis of nanoparticles. The biological extract and AgNO3 were blended and heated to synthesize AgNPs. The reaction process was monitored using UV-Visible spectroscopy. Fourier Transfer Infrared spectroscopy (FTIR) was used for the characterization of biological compounds and their substituent groups before and after the reaction process. Dynamic Light scattering (DLS) method was used to characterize particle size of AgNPs and their biomolecular stability. Results showed that biological compounds such as aliphatic amines, alkenes (=C-H), alkanes (C-H), alcohol (O-H) and unsaturated esters(C-O), which has an average particle size of 109 and 215.8 nm and polydispersity index of 0.451 and 0.375 for ethanol and water extract, respectively. According to TEM measurements the size of AgNPs are in the range 5-20 nm The results suggested that ethanol derived AgNPs contained higher yield of organic compounds, thus has better solubility power than water. Ag NPs can be used to control salmonella in poultry industry.

Kuponiyi, Abiola; Kassama, Lamin; Kukhtareva, Tatiana

2014-08-01

37

Cytotoxicity of Biologically Synthesized Silver Nanoparticles in MDA-MB-231 Human Breast Cancer Cells  

PubMed Central

Silver nanoparticles (AgNPs) have been used as an antimicrobial and disinfectant agents. However, there is limited information about antitumor potential. Therefore, this study focused on determining cytotoxic effects of AgNPs on MDA-MB-231 breast cancer cells and its mechanism of cell death. Herein, we developed a green method for synthesis of AgNPs using culture supernatant of Bacillus funiculus, and synthesized AgNPs were characterized by various analytical techniques such as UV-visible spectrophotometer, particle size analyzer, and transmission electron microscopy (TEM). The toxicity was evaluated using cell viability, metabolic activity, and oxidative stress. MDA-MB-231 breast cancer cells were treated with various concentrations of AgNPs (5 to 25??g/mL) for 24?h. We found that AgNPs inhibited the growth in a dose-dependent manner using MTT assay. AgNPs showed dose-dependent cytotoxicity against MDA-MB-231 cells through activation of the lactate dehydrogenase (LDH), caspase-3, reactive oxygen species (ROS) generation, eventually leading to induction of apoptosis which was further confirmed through resulting nuclear fragmentation. The present results showed that AgNPs might be a potential alternative agent for human breast cancer therapy. PMID:23936814

Gurunathan, Sangiliyandi; Han, Jae Woong; Eppakayala, Vasuki; Jeyaraj, Muniyandi; Kim, Jin-Hoi

2013-01-01

38

Silver Nanoparticles in Dental Biomaterials  

PubMed Central

Silver has been used in medicine for centuries because of its antimicrobial properties. More recently, silver nanoparticles have been synthesized and incorporated into several biomaterials, since their small size provides great antimicrobial effect, at low filler level. Hence, these nanoparticles have been applied in dentistry, in order to prevent or reduce biofilm formation over dental materials surfaces. This review aims to discuss the current progress in this field, highlighting aspects regarding silver nanoparticles incorporation, such as antimicrobial potential, mechanical properties, cytotoxicity, and long-term effectiveness. We also emphasize the need for more studies to determine the optimal concentration of silver nanoparticle and its release over time. PMID:25667594

Corrêa, Juliana Mattos; Mori, Matsuyoshi; Sanches, Heloísa Lajas; da Cruz, Adriana Dibo; Poiate, Isis Andréa Venturini Pola

2015-01-01

39

pH effect on the aggregation of silver nanoparticles synthesized by chemical reduction  

NASA Astrophysics Data System (ADS)

Silver colloidal nanoparticles were prepared according to the chemical reduction method in which the ascorbic acid was used as a reducing agent and sodium citrate as a stabilizing agent. The absorption spectra of all prepared samples obtained using the UV-Vis spectrophotometer showed a surface plasmon peak at a wavelength of about 420 nm. The size of the silver nanoparticles was controlled by changing the pH values of the reaction system. At high pH, smaller size silver nanoparticles were obtained compared to low pH values. This difference can be attributed to the difference in the reduction rate of the precursor. In addition to the inverse proportionality between the size and the pH value it is clear that increasing the pH value enables us to obtain spherical nanoparticles while at low pH, rods and triangular particle shapes were formed. Poor balance between nucleation and growth processes could be the cause of this result.

Alqadi, M. K.; Abo Noqtah, O. A.; Alzoubi, F. Y.; Alzouby, J.; Aljarrah, K.

2014-01-01

40

Antibacterial properties of silver nanoparticles synthesized using Pulicaria glutinosa plant extract as a green bioreductant  

PubMed Central

The antibacterial properties of nanoparticles (NPs) can be significantly enhanced by increasing the wettability or solubility of NPs in aqueous medium. In this study, we investigated the effects of the stabilizing agent on the solubility of silver NPs and its subsequent effect on their antimicrobial activities. Silver NPs were prepared using an aqueous solution of Pulicaria glutinosa plant extract as bioreductant. The solution also acts as a capping ligand. During this study, the antimicrobial activities of silver NPs, as well as the plant extract alone, were tested against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Micrococcus luteus. Silver NPs were prepared with various concentrations of the plant extract to study its effect on antimicrobial activity. Interestingly, various concentrations of P. glutinosa extract did not show any effect on the growth of tested bacteria; however, a significant effect on the antimicrobial property of plant extract capped silver NPs (Ag-NPs-PE) was observed. For instance, the half maximal inhibitory concentration values were found to decrease (from 4% to 21%) with the increasing concentrations of plant extract used for the synthesis of Ag-NPs-PE. These results clearly indicate that the addition of P. glutinosa extracts enhances the solubility of Ag-NPs-PE and, hence, increases their toxicity against the tested microorganisms. PMID:25114525

Khan, Mujeeb; Khan, Shams Tabrez; Khan, Merajuddin; Adil, Syed Farooq; Musarrat, Javed; Al-Khedhairy, Abdulaziz A; Al-Warthan, Abdulrahman; Siddiqui, Mohammed Rafiq H; Alkhathlan, Hamad Z

2014-01-01

41

Antibacterial and cytotoxic effect of biologically synthesized silver nanoparticles using aqueous root extract of Erythrina indica lam.  

PubMed

Simple, yet an effective and rapid approach for the green synthesis of silver nanoparticles (Ag NPs) using root extract of Erythrina indica and its in vitro antibacterial activity was tried against human pathogenic bacteria and its cytotoxic effect in breast and lung cancer cell lines has been demonstrated in this study. Various instrumental techniques were adopted to characterize the synthesized Ag NPs viz. UV-Vis (Ultra violet), FTIR (Fourier Transform Infrared), XRD (X-ray diffraction), DLS (Dynamic light scattering), HR TEM (High-resolution transmission electron microscopy), EDX (Energy-dispersive X-ray spectroscopy). Surface plasmon spectra for Ag NPs are centered nearly at 438 nm with dark brown color. FTIR analysis revealed the presence of terpenes, phenol, flavonols and tannin act as effective reducing and capping agents for converting silver nitrate to Ag NPs. The synthesized Ag NPs were found to be spherical in shape with size in the range of 20-118 nm. Moreover, the synthesized Ag NPs showed potent antibacterial activity against Gram positive and Gram negative bacteria and these biologically synthesized nanoparticles were also proved to exhibit excellent cytotoxic effect on breast and lung cancer cell lines. PMID:25189525

Rathi Sre, P R; Reka, M; Poovazhagi, R; Arul Kumar, M; Murugesan, K

2015-01-25

42

Antibacterial and cytotoxic effect of biologically synthesized silver nanoparticles using aqueous root extract of Erythrina indica lam  

NASA Astrophysics Data System (ADS)

Simple, yet an effective and rapid approach for the green synthesis of silver nanoparticles (Ag NPs) using root extract of Erythrina indica and its in vitro antibacterial activity was tried against human pathogenic bacteria and its cytotoxic effect in breast and lung cancer cell lines has been demonstrated in this study. Various instrumental techniques were adopted to characterize the synthesized Ag NPs viz. UV-Vis (Ultra violet), FTIR (Fourier Transform Infrared), XRD (X-ray diffraction), DLS (Dynamic light scattering), HR TEM (High-resolution transmission electron microscopy), EDX (Energy-dispersive X-ray spectroscopy). Surface plasmon spectra for Ag NPs are centered nearly at 438 nm with dark brown color. FTIR analysis revealed the presence of terpenes, phenol, flavonols and tannin act as effective reducing and capping agents for converting silver nitrate to Ag NPs. The synthesized Ag NPs were found to be spherical in shape with size in the range of 20-118 nm. Moreover, the synthesized Ag NPs showed potent antibacterial activity against Gram positive and Gram negative bacteria and these biologically synthesized nanoparticles were also proved to exhibit excellent cytotoxic effect on breast and lung cancer cell lines.

Rathi Sre, P. R.; Reka, M.; Poovazhagi, R.; Arul Kumar, M.; Murugesan, K.

2015-01-01

43

Combined efficacy of biologically synthesized silver nanoparticles and different antibiotics against multidrug-resistant bacteria  

PubMed Central

Biological synthesis of nanoparticles is a growing innovative approach that is relatively cheaper and more environmentally friendly than current physicochemical processes. Among various microorganisms, fungi have been found to be comparatively more efficient in the synthesis of nanomaterials. In this research work, extracellular mycosynthesis of silver nanoparticles (AgNPs) was probed by reacting the precursor salt of silver nitrate (AgNO3) with culture filtrate of Aspergillus flavus. Initially, the mycosynthesis was regularly monitored by ultraviolet-visible spectroscopy, which showed AgNP peaks of around 400–470 nm. X-ray diffraction spectra revealed peaks of different intensities with respect to angle of diffractions (2?) corresponding to varying configurations of AgNPs. Transmission electron micrographs further confirmed the formation of AgNPs in size ranging from 5–30 nm. Combined and individual antibacterial activities of the five conventional antibiotics and AgNPs were investigated against eight different multidrug-resistant bacterial species using the Kirby–Bauer disk-diffusion method. The decreasing order of antibacterial activity (zone of inhibition in mm) of antibiotics, AgNPs, and their conjugates against bacterial group (average) was; ciprofloxacin + AgNPs (23) . imipenem + AgNPs (21) > gentamycin + AgNPs (19) > vancomycin + AgNPs (16) > AgNPs (15) . imipenem (14) > trimethoprim + AgNPs (14) > ciprofloxacin (13) > gentamycin (11) > vancomycin (4) > trimethoprim (0). Overall, the synergistic effect of antibiotics and nanoparticles resulted in a 0.2–7.0 (average, 2.8) fold-area increase in antibacterial activity, which clearly revealed that nanoparticles can be effectively used in combination with antibiotics in order to improve their efficacy against various pathogenic microbes. PMID:23986635

Naqvi, Syed Zeeshan Haider; Kiran, Urooj; Ali, Muhammad Ishtiaq; Jamal, Asif; Hameed, Abdul; Ahmed, Safia; Ali, Naeem

2013-01-01

44

Spectroscopy investigation on chemo-catalytic, free radical scavenging and bactericidal properties of biogenic silver nanoparticles synthesized using Salicornia brachiata aqueous extract  

NASA Astrophysics Data System (ADS)

Nanosized silver have been widely used in many applications, such as catalysis, photonics, sensors, medicine etc. Thus, there is an increasing need to develop high-yield, low cost, non-toxic and eco-friendly procedures for the synthesis of nanoparticles. Herein, we report an efficient, green synthesis of silver nanoparticles utilizing the aqueous extract of Salicornia brachiata, a tropical plant of the Chenopodiaceae family. Silver nanoparticles have been characterized by ultraviolet-visible spectroscopy, scanning electron microscopy and transmission electron microscopy. The morphology of the particles formed consists of highly diversified shapes like spherical, rod-like, prism, triangular, pentagonal and hexagonal pattern. However, addition of sodium hydroxide to the extract produces mostly spherical particles. The stable nanoparticles obtained using this green method show remarkable catalytic activity in the reduction of 4-nitro phenol to 4-amino phenol. The reduction catalyzed by silver nanoparticles followed the first-order kinetics, with a rate constant of, 0.6 × 10-2 s-1. The bactericidal activity of the synthesized silver nanoparticles against the pathogenic bacteria, Staphylococcus aureus, Staphylococcus aureus E, Bacillus subtilis and Escherichia coli, was also explored using REMA. The obtained results showed that the minimum inhibitory concentration required to induce bactericidal effect is lower than the control antibiotic, ciprofloxacin. In addition to these, the biogenic synthesized nanoparticles also exhibited excellent free radical scavenging activity.

Seralathan, Janani; Stevenson, Priscilla; Subramaniam, Shankar; Raghavan, Rachana; Pemaiah, Brindha; Sivasubramanian, Aravind; Veerappan, Anbazhagan

2014-01-01

45

New procedure to synthesize silver nanoparticles and their interaction with local anesthetics  

PubMed Central

Silver nanoparticles (AgNPs) were prepared in aqueous colloid dispersions by the reduction of Ag+ with glucose in alkaline medium. Tetraethyl orthosilicate and L-asparagine were added as stabilizers of NPs. The AgNPs were characterized, and their interaction with three local anesthetics (procaine, dibucaine, or tetracaine) was investigated. Optical spectra show the characteristic absorption band of AgNPs, due to surface plasmon resonance. Modifications in the position and shape of this band reflect the self-assembly of metal NPs mediated by anesthetic molecules and the progress in time of the aggregation process. Zeta-potential measuring was applied in order to characterize the electrostatic stability of the NPs. The size and shape of the AgNPs, as well as the features of the assemblies formed by their association in the presence of anesthetics, were evidenced by transmission electron microscopy images. Atomic force microscopy images showed the characteristics of the films of AgNPs deposited on glass support. The effect of the anesthetics could be described in terms of electrostatic forces between the negatively charged AgNPs and the anesthetic molecules, existing also in their cationic form at the working pH. But also hydrophobic and hydrogen bonding interactions between the coated nanoparticles and anesthetics molecular species should be considered. PMID:24143090

Mocanu, Aurora; Pasca, Roxana Diana; Tomoaia, Gheorghe; Garbo, Corina; Frangopol, Petre T; Horovitz, Ossi; Tomoaia-Cotisel, Maria

2013-01-01

46

Mechanistic antimicrobial approach of extracellularly synthesized silver nanoparticles against gram positive and gram negative bacteria.  

PubMed

The development of eco-friendly and reliable processes for the synthesis of nanoparticles has attracted considerable interest in nanotechnology. In this study, an extracellular enzyme system of a newly isolated microorganism, Exiguobacterium sp. KNU1, was used for the reduction of AgNO? solutions to silver nanoparticles (AgNPs). The extracellularly biosynthesized AgNPs were characterized by UV-vis spectroscopy, Fourier transform infra-red spectroscopy and transmission electron microscopy. The AgNPs were approximately 30 nm (range 5-50 nm) in size, well-dispersed and spherical. The AgNPs were evaluated for their antimicrobial effects on different gram negative and gram positive bacteria using the minimum inhibitory concentration method. Reasonable antimicrobial activity against Salmonella typhimurium, Pseudomonas aeruginosa, Escherichia coli and Staphylococcus aureus was observed. The morphological changes occurred in all the microorganisms tested. In particular, E. coli exhibited DNA fragmentation after being treated with the AgNPs. Finally, the mechanism for their bactericidal activity was proposed according to the results of scanning electron microscopy and single cell gel electrophoresis. PMID:23867968

Tamboli, Dhawal P; Lee, Dae Sung

2013-09-15

47

Silver sulfide nanoparticles sensitized titanium dioxide nanotube arrays synthesized by in situ sulfurization for photocatalytic hydrogen production.  

PubMed

Titanium dioxide (TiO2) nanotube arrays (TNAs) sensitized with silver sulfide (Ag2S) nanoparticles (NPs) were synthesized via facile in situ sulfurization. Metallic silver NPs were first loaded on TNAs through a simple electrodeposition process. The as-prepared Ag/TNAs composites were further treated with a solution of acetonitrile containing sulfur (S8) and dried in vacuum to obtain a new nanocomposite material comprising of TNAs sensitized with Ag2S NPs. In these composite nanostructures, ultrafine Ag2S NPs were well-dispersed and assembled on the exterior and interior walls of the TNAs. Owing to sensitizing with a narrow bandgap material like Ag2S and the homogeneous distribution of the Ag2S NP heterojunction structures over the surface of the TNAs, the synthesized nanocomposite samples exhibited remarkable capability to absorb visible light and showed a significant enhancement in the photocatalytic efficiency of hydrogen generation. Under visible light illumination (100mW/cm(2)), a maximum photoconversion efficiency of 1.21% and the highest hydrogen production rate of 1.13mL/cm(2)h were obtained from the TNA electrodes sensitized with Ag2S NPs. PMID:24183425

Liu, Xu; Liu, Zhongqing; Lu, Jinlin; Wu, Xuelian; Chu, Wei

2014-01-01

48

Lousicidal activity of synthesized silver nanoparticles using Lawsonia inermis leaf aqueous extract against Pediculus humanus capitis and Bovicola ovis.  

PubMed

In the present work, we describe inexpensive, nontoxic, unreported and simple procedure for synthesis of silver nanoparticles (Ag NPs) using leaf aqueous extract of Lawsonia inermis as eco-friendly reducing and capping agent. The aim of the present study was to assess the lousicidal activity of synthesized Ag NPs against human head louse, Pediculus humanus capitis De Geer (Phthiraptera: Pediculidae), and sheep body louse, Bovicola ovis Schrank (Phthiraptera: Trichodectidae). Direct contact method was conducted to determine the potential of pediculocidal activity and impregnated method was used with slight modifications to improve practicality and efficiency of tested materials of synthesized Ag NPs against B. ovis. The synthesized Ag NPs characterized with the UV showing peak at 426 nm. X-ray diffraction (XRD) spectra clearly shows that the diffraction peaks in the pattern indexed as the silver with lattice constants. XRD analysis showed intense peaks at 2? values of 38.34°, 44.59°, 65.04°, and 77.77° corresponding to (111), (200), (220), and (311) Bragg's reflection based on the fcc structure of Ag NPs. Fourier transform infrared spectroscopy (FTIR) spectra of Ag NPs exhibited prominent peaks at 3,422.13, 2,924.12, 2,851.76, 1,631.41, 1,381.60, 1,087.11, and 789.55 cm(-1). Scanning electron microscopy (SEM) micrograph showed mean size of 59.52 nm and aggregates of spherical shape Ag NPs. Energy dispersive X-ray spectroscopy (EDX) showed the complete chemical composition of the synthesized Ag NPs. In pediculocidal activity, the results showed that the optimal times for measuring percent mortality effects of synthesized Ag NPs were 26, 61, 84, and 100 at 5, 10, 15, and 20 min, respectively. The average percent mortality for synthesized Ag NPs was 33, 84, 91, and 100 at 10, 15, 20, and 35 min, respectively against B. ovis. The maximum activity was observed in the aqueous leaf extract of L. inermis, 1 mM AgNO(3) solution, and synthesized Ag NPs against P. humanus capitis with LC(50) values of 18.26, 7.77, and 1.33 mg l(-1) and r (2) values of 0.863, 0.900, and 0.803 and against B. ovis showed with LC(50) values of 21.19, 8.49, and 1.41 mg l(-1) and r (2) values of 0.920, 0.938 and 0.870, respectively. The findings revealed that synthesized Ag NPs possess excellent anti-lousicidal activity. PMID:21993881

Marimuthu, Sampath; Rahuman, Abdul Abdul; Santhoshkumar, Thirunavukkarasu; Jayaseelan, Chidambaram; Kirthi, Arivarasan Vishnu; Bagavan, Asokan; Kamaraj, Chinnaperumal; Elango, Gandhi; Zahir, Abdul Abduz; Rajakumar, Govindasamy; Velayutham, Kanayairam

2012-11-01

49

Anti-Angiogenesis Effect of Biogenic Silver Nanoparticles Synthesized Using Saliva officinalis on Chick Chorioalantoic Membrane (CAM).  

PubMed

Angiogenesis, which is required for physiological events, plays a crucial role in several pathological conditions, such as tumor growth and metastasis. The use of plant extracts is a cost effective and eco-friendly way to synthesize nanoparticles. In the present study, we investigated the anti-angiogenesis properties of silver nanoparticles synthesized using Saliva officinalis extract on chick chorioalantoic membrane. The production of nanoparticles was confirmed by the color change from yellow to brown observed after approximately 3 h at 37 °C. Then, the nanoparticles were characterized by UV-visible spectroscopy, FTIR, and TEM. The UV-visible spectroscopy results showed that the surface plasmon resonance band for AgNPs was around 430 nm. The intensity of the AgNP-specific absorption peak improved with an increase of 0.5 mL of extract into 10 mL of AgNO3 (2.5 mM). The FTIR results showed good interaction between the plant extracts and AgNPs. The TEM images of the samples revealed that the NPs varied in morphology and size from 1 to 40 nm; the average was recorded at 16.5 ± 1.2 nm. Forty Ross fertilized eggs were divided into four groups; the control and three experimental groups. On the 8th day, gelatin sponges containing albumin were placed on the chorioalantoic membrane and soaked with different concentrations of NPs. On the 12th day, all the cases were photographed using a photostereomicroscope. The number and the lengths of the vessels were measured using Image J software. The crown rump (CR) and weight of the embryo were also recorded. Then the hemoglobin content was measured using Drabkin's reagent kit for quantification of the blood vessel formation. According to the data analysis, the number and length of the blood vessels, as well as the CR and weight of the embryos reduced significantly compared to the control (p < 0.05), dose dependently. The total hemoglobin was quantified as an indicator of the blood vessel formation. The hemoglobin content in the treated samples with AgNPs decreased, which showed its inhibitory effect on angiogenesis. PMID:25255752

Baharara, Javad; Namvar, Farideh; Mousavi, Marzieh; Ramezani, Tayebe; Mohamad, Rosfarizan

2014-01-01

50

Adulticidal properties of synthesized silver nanoparticles using leaf extracts of Feronia elephantum (Rutaceae) against filariasis, malaria, and dengue vector mosquitoes.  

PubMed

Mosquito-borne diseases with an economic impact create loss in commercial and labor outputs, particularly in countries with tropical and subtropical climates. Mosquito control is facing a threat because of the emergence of resistance to synthetic insecticides. Extracts from plants may be alternative sources of mosquito control agents because they constitute a rich source of bioactive compounds that are biodegradable into nontoxic products and potentially suitable for use to control mosquitoes. Insecticides of botanical origin may serve as suitable alternative biocontrol techniques in the future. In view of the recently increased interest in developing plant origin insecticides as an alternative to chemical insecticide, in the present study, the adulticidal activity of silver nanoparticles (AgNPs) synthesized using Feronia elephantum plant leaf extract against adults of Anopheles stephensi, Aedes aegypti, and Culex quinquefasciatus was determined. The range of concentrations of synthesized AgNPs (8, 16, 24, 32, and 40 ?g mL(-1)) and aqueous leaf extract (40, 80, 120, 160, and 200 ?g mL(-1)) were tested against the adults of A. stephensi, A. aegypti, and C. quinquefasciatus. Adults were exposed to varying concentrations of aqueous crude extract and synthesized AgNPs for 24 h. Considerable mortality was evident after the treatment of F. elephantum for all three important vector mosquitoes. The synthesized AgNPs from F. elephantum were highly toxic than crude leaf aqueous extract to three important vector mosquito species. The results were recorded from UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy analysis (EDX), and transmission electron microscopy (TEM). Synthesized AgNPs against the vector mosquitoes A. stephensi, A. aegypti, and C. quinquefasciatus had the following lethal dose (LD)?? and LD?? values: A. stephensi had LD?? and LD?? values of 18.041 and 32.575 ?g mL(-1); A. aegypti had LD?? and LD?? values of 20.399 and 37.534 ?g mL(-1); and C. quinquefasciatus had LD?? and LD?? values of 21.798 and 39.596 ?g mL(-1). No mortality was observed in the control. These results suggest that the leaf aqueous extracts of F. elephantum and green synthesis of AgNPs have the potential to be used as an ideal eco-friendly approach for the control of the A. stephensi, A. aegypti, and C. quinquefasciatus. This is the first report on the adulticidal activity of the plant extracts and AgNPs. PMID:25146645

Veerakumar, Kaliyan; Govindarajan, Marimuthu

2014-11-01

51

Antibacterial activities of silver nanoparticles and antibiotic-adsorbed silver nanoparticles against biorecycling microbes.  

PubMed

Silver nanoparticles have a huge share in nanotechnology based products used in clinical and hygiene products. Silver nanoparticles leaching from these medical and domestic products will eventually enter terrestrial ecosystems and will interact with the microbes present in the land and water. These interactions could be a threat to biorecycling microbes present in the Earth's crust. The antimicrobial action towards biorecycling microbes by leached silver nanoparticles from medical waste could be many times greater compared to that of silver nanoparticles leached from other domestic products, since medical products may contain traditional antibiotics along with silver nanoparticles. In the present article, we have evaluated the antimicrobial activities of as-synthesized silver nanoparticles, antibiotics - tetracycline and kanamycin, and antibiotic-adsorbed silver nanoparticles. The antimicrobial action of silver nanoparticles with adsorbed antibiotics is 33-100% more profound against the biorecycling microbes B. subtilis and Pseudomonas compared to the antibacterial action of silver nanoparticles of the same concentration. This study indicates that there is an immediate and urgent need for well-defined protocols for environmental exposure to silver nanoparticles, as the use of silver nanoparticles in nanotechnology based products is poorly restricted. PMID:25000128

Khurana, Chandni; Vala, Anjana K; Andhariya, Nidhi; Pandey, O P; Chudasama, Bhupendra

2014-09-20

52

Silver nanoparticles synthesized by pulsed laser ablation: as a potent antibacterial agent for human enteropathogenic gram-positive and gram-negative bacterial strains.  

PubMed

Present investigation deals with the study, to quantify the antibacterial property of silver nanoparticles (SNPs), synthesized by pulsed laser ablation (PLA) in aqueous media, on some human enteropathogenic gram-positive and gram-negative bacterial strains. Antibacterial property was studied by measuring the zone of inhibition using agar cup double-diffusion method, minimum inhibitory concentration by serial dilution method, and growth curve for 24 h. The results clearly show the potency of antibacterial property of PLA-synthesized SNPs and suggest that it can be used as an effective growth inhibitor against various pathogenic bacterial strains in various medical devices and antibacterial control systems. PMID:24801405

Pandey, Jitendra Kumar; Swarnkar, R K; Soumya, K K; Dwivedi, Priyanka; Singh, Manish Kumar; Sundaram, Shanthy; Gopal, R

2014-10-01

53

Synthesis of Silver Nanoparticles  

NSDL National Science Digital Library

This series of videos, presented by the Materials Research Science and Engineering Center at the University of Wisconsin-Madison, deals with the synthesis of silver nanoparticles. The experiment allows students to view the formation of silver nanoparticles that can be detected by the reflection of a laser beam. Silver nanoparticles are used in the creation of yellow stained glass in churches around the country, an interesting, but little known fact. This is a fairly inexpensive activity as it involves stock solutions, and equipment present in any science laboratory. Overall, students will enjoy this basic, but still challenging, experiment.

Johnson, Chris

54

Biosynthesis of silver nanoparticles by Leishmania tropica  

Microsoft Academic Search

Biosynthesis and characterizations of nanoparticles have become an important branch of nanotechnology. A novel biosynthesis route for Silver Nanoparticles (Ag-NPs) was attempted in the present study using Leishmania tropica the causative agent of cutaneous leishmaniasis in different countries, particularly in Mediterranean region in Iraq. Silver nanoparticles were successfully synthesized from AgNO3 by reduction of aqueous Ag+ ions with the cell

Abdulsadah A. Rahi; Magda A. Ali; Alaa H. Al-Charrakh

2013-01-01

55

Physiological, metabolic, and transcriptional effects of biologically-synthesized silver nanoparticles in turnip (Brassica rapa ssp. rapa L.).  

PubMed

Silver nanoparticles (AgNPs) use has been increased in recent years, which has potentially antagonistic effects on living organisms, including microbes, human, and plants. The physiological and molecular responses of AgNPs have been reported for several plants; however, the detailed mechanism of action of AgNPs is not known in turnip. Accordingly, the aim of this study was determined to evaluate the impact of AgNPs exposure in turnip seedlings at concentrations up to 10.0 mg/l. The frequency of seed germination decreased with increasing AgNPs concentration. Moreover, while exposure to 1.0 mg/l AgNPs significantly increased plant fresh biomass. The plant growth, biomass, and chlorophyll content were decreased at 5.0 and 10.0 mg/l AgNPs. Anthocyanin, malondialdehyde, and hydrogen peroxide levels were significantly increased with higher concentrations of AgNPs. Furthermore, reactive oxygen species (ROS) production and DNA damage were significantly elevated in plants treated with higher concentrations of AgNPs. The DNA damage potential was confirmed in the experiment of DNA laddering, comet, and TUNEL assays. Consequently, the study confirms the phytotoxic, cytotoxic, and genotoxic potentials induced by AgNPs. Moreover, higher concentrations (5.0 and 10.0 mg/l) of AgNPs significantly induced expression of genes related to glucosinolates and phenolics biosynthesis as well as abiotic and biotic stresses whereas down-regulated the carotenoid gene expressions. To our knowledge, this is the first report to evaluate the physiological, metabolic, and transcriptional responses of turnip to biologically synthesized AgNPs. PMID:25471476

Thiruvengadam, Muthu; Gurunathan, Sangiliyandi; Chung, Ill-Min

2014-12-01

56

The green synthesis, characterization, and evaluation of the biological activities of silver nanoparticles synthesized from Leptadenia reticulata leaf extract  

NASA Astrophysics Data System (ADS)

Biosynthesis of silver nanoparticles (Ag Nps) was carried out using methanol leaves extract of L. reticulata. Ag Nps were characterized based on the observations of UV-visible spectroscopy, transmission electron microscopy, and X-ray diffraction (XRD) analysis. These Ag Nps were tested for antimicrobial activity by agar well diffusion method against different pathogenic microorganisms and antioxidant activity was performed using DPPH assay. Further, the in vitro cytotoxic effects of Ag Nps were screened against HCT15 cancer cell line and viability of tumor cells was confirmed using MTT ((3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole)) assay. The nuclear condensation was studied using the propidium iodide-staining method. The color change from green to dark brown and the absorbance peak at about 420 nm indicated the formation of nanoparticles. XRD pattern showed characteristic peaks indexed to the crystalline planes (111), (200) and (220) of face-centered cubic silver. The nanoparticles were of spherical shape with varying sizes ranging from 50 to 70 nm. Biosynthesized Ag Nps showed potent antibacterial activity and effective radical scavenging activity. MTT assay revealed a dose-dependent decrease in cell viability. Microscopic observations showed distinct cellular morphological changes indicating unhealthy cells, whereas the control appeared normal. Increase in the number of propidium iodide positive cells were observed in maximum concentration. Methanolic leaf extract of L. reticulata acts as an excellent capping agent for the formation of silver nanoparticles and demonstrates immense biological activities. Hence, these Ag NPs can be used as antibacterial, antioxidant as well as cytotoxic agent in treating many medical complications.

Kumara Swamy, M.; Sudipta, K. M.; Jayanta, K.; Balasubramanya, S.

2015-01-01

57

The green synthesis, characterization, and evaluation of the biological activities of silver nanoparticles synthesized from Leptadenia reticulata leaf extract  

NASA Astrophysics Data System (ADS)

Biosynthesis of silver nanoparticles (Ag Nps) was carried out using methanol leaves extract of L. reticulata. Ag Nps were characterized based on the observations of UV-visible spectroscopy, transmission electron microscopy, and X-ray diffraction (XRD) analysis. These Ag Nps were tested for antimicrobial activity by agar well diffusion method against different pathogenic microorganisms and antioxidant activity was performed using DPPH assay. Further, the in vitro cytotoxic effects of Ag Nps were screened against HCT15 cancer cell line and viability of tumor cells was confirmed using MTT ((3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, a yellow tetrazole)) assay. The nuclear condensation was studied using the propidium iodide-staining method. The color change from green to dark brown and the absorbance peak at about 420 nm indicated the formation of nanoparticles. XRD pattern showed characteristic peaks indexed to the crystalline planes (111), (200) and (220) of face-centered cubic silver. The nanoparticles were of spherical shape with varying sizes ranging from 50 to 70 nm. Biosynthesized Ag Nps showed potent antibacterial activity and effective radical scavenging activity. MTT assay revealed a dose-dependent decrease in cell viability. Microscopic observations showed distinct cellular morphological changes indicating unhealthy cells, whereas the control appeared normal. Increase in the number of propidium iodide positive cells were observed in maximum concentration. Methanolic leaf extract of L. reticulata acts as an excellent capping agent for the formation of silver nanoparticles and demonstrates immense biological activities. Hence, these Ag NPs can be used as antibacterial, antioxidant as well as cytotoxic agent in treating many medical complications.

Kumara Swamy, M.; Sudipta, K. M.; Jayanta, K.; Balasubramanya, S.

2014-02-01

58

A comparative study of morphology, reactivity and stability of synthesized silver nanoparticles using Bacillus subtilis and Catharanthus roseus (L.) G. Don  

Microsoft Academic Search

Large number of papers has been published recently on the eleventh group metallic elements such as Ag, Au and Cu. Our study was focused on biosynthesis of silver nanoparticles, their morphology, reactivity and stability. We were interested to check these properties in two different samples, S1 and S2, respectively. The biosynthesis of silver nanoparticles was achieved by reacting the samples

N. Kannan; K. S. Mukunthan; S. Balaji

2011-01-01

59

Biomimetic synthesis and patterning of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The creation of nanoscale materials for advanced structures has led to a growing interest in the area of biomineralization. Numerous microorganisms are capable of synthesizing inorganic-based structures. For example, diatoms use amorphous silica as a structural material, bacteria synthesize magnetite (Fe3O4) particles and form silver nanoparticles, and yeast cells synthesize cadmium sulphide nanoparticles. The process of biomineralization and assembly of nanostructured inorganic components into hierarchical structures has led to the development of a variety of approaches that mimic the recognition and nucleation capabilities found in biomolecules for inorganic material synthesis. In this report, we describe the in vitro biosynthesis of silver nanoparticles using silver-binding peptides identified from a combinatorial phage display peptide library.

Naik, Rajesh R.; Stringer, Sarah J.; Agarwal, Gunjan; Jones, Sharon E.; Stone, Morley O.

2002-11-01

60

Bioconjugation of gold and silver nanoparticles synthesized by Fusarium oxysporum and their use in rapid identification of Candida species by using bioconjugate-nano-polymerase chain reaction.  

PubMed

We developed a Bioconjugate-Nano-PCR as a rapid and specific method for identification of Candida species in less time. This requires very low concentration of master mix and DNA sample of Candida albicans in conjugation with gold nanoparticles (AuNPs) and silver nanoparticles (AgNPs). We report a modification of the PCR assay with nanoparticles that allows the detection of high fidelity amplification of ITS-rDNA and beta (beta) tubulin gene of Candida species from low concentrated DNA in short period. We synthesized and characterized the covalently attached 34 nm (AuNPs) and 35 nm of (AgNPs) and conjugated with C. albicans DNA sample, which is used as a template for PCR. The use of this nanoparticle modified template improves the sensitivity and specificity of the traditional PCR assay with very low cycles which is very helpful in molecular diagnostics and therapeutics. It proves to be an effective method for identification of Candida species with low concentration of DNA. This type of PCR assay is useful for detection of target gene by enhancing the specificity of the target gene and is less time consuming. PMID:24266252

Bansod, Sunita; Bonde, Shital; Tiwari, Vaibhav; Bawaskar, Manisha; Deshmukh, Shivaji; Gaikwad, Swapnil; Gade, Aniket; Rai, Mahendra

2013-12-01

61

Biofabrication of silver nanoparticles using Andrographis paniculata.  

PubMed

New and novel strategies are of recent interest in the development of silver nanoparticles. The plant extracts are eco-friendly, economical and cost effective for synthesis of nanoparticles. In this paper, we represent biofabrication of silver nanoparticles (AgNPs) using Andrographis paniculata and the synthesized AgNPs was monitored by ultra-violet visible spectroscopy (UV-Vis). The morphology and crystalline nature of AgNPs were determined from scanning electron microscopy (SEM) with Energy dispersive X-ray (EDX), X-ray diffraction patterns (XRD), Fourier transform-infrared spectroscopy (FT-IR). The size and the stability were detected by using Nanoparticle analyzer. The average size of the AgNPs was found to be 54 ± 2 nm and the Zeta potential was found to be -50.7 mV. The synthesized AgNPs have very good antifungal activity. PMID:24389508

Kotakadi, Venkata S; Gaddam, Susmila Aparna; Subba Rao, Y; Prasad, T N V K V; Varada Reddy, A; Sai Gopal, D V R

2014-02-12

62

Syntheses and characterization of nearly monodispersed, size-tunable silver nanoparticles over a wide size range of 7-200 nm by tannic acid reduction.  

PubMed

Nearly monodispersed spherical silver nanoparticles (Ag NPs) were synthesized by using tannic acid (TA) as both reductant and stabilizer in a 30 °C water bath. The size of the as-prepared Ag NPs could be tuned in a range of 7-66 nm by changing the molar ratio of TA to silver nitrate and pH of the reaction solutions. UV-vis spectra, TEM observations, and temporal evolution of the monomer concentrations for the reactions carried out at different experimental conditions showed that the improved size distribution and size tunability of the Ag NPs were mainly attributed to the use of TA, which could promote the balance of nucleation and growth processes of the NPs effectively. The size of the Ag NPs was extendable up to 200 nm in one-pot fashion by the multi-injection approach. The size-dependent surface-enhanced Raman scattering (SERS) activity of the as-prepared Ag NPs was evaluated, and the NPs with size around 100 nm were identified to show a maximum enhanced factor of 3.6 × 10(5). Moreover, the as-prepared TA-coated Ag NPs presented excellent colloidal stability compared to the conventional citrate-coated ones. PMID:24628127

Cao, Yanzhen; Zheng, Rongfeng; Ji, Xiaohui; Liu, Hong; Xie, Renguo; Yang, Wensheng

2014-04-01

63

Antimicrobial Properties of Silver Nanoparticles  

NSDL National Science Digital Library

This module provides students the opportunity to "explore silver nanoparticles and their effectiveness against bacterial growth in hands-on laboratory activities." Students first make silver nanoparticles and then use them in an experiment they design. This lesson will require two or more class periods and is aimed at secondary students.The document is available to download in PDF file format.

Kouadio, Carrie

64

Antimicrobial activity of silver nanoparticles impregnated wound dressing  

NASA Astrophysics Data System (ADS)

In this work, silver nanoparticles were synthesized by simple wet chemical reduction method. The silver nitrate was reduced by Sodium borohydride used as reducing agent and Poly (vinyl pyrrolidone) (PVP) as stabilizing agent. The formation of silver nanoparticles was evaluated by UV-visible spectroscope and transmission electron microscope (TEM). Absorption spectrum consist two plasmon peaks at 410 and 668 nm revels the formation of anisotropic nanoparticles confirmed by TEM. The formation of silver nanoparticles was also evidenced by dynamic light scattering (DLS) study. DLS showed polydisperse silver nanoparticles with hydrodynamic size 32 nm. Protecting mechanism of PVP was manifested by FT-Raman study. Silver nanoparticles were impregnated into wound dressing by sonochemical method. The Kirby-Bauer disc diffusion methods were used for antimicrobial susceptibility testing. The antimicrobial activity of the samples has been tested against gram-negative bacterium Escherichia coli and gram-positive bacterium Staphylococcus aureus.

Shinde, V. V.; Jadhav, P. R.; Patil, P. S.

2013-06-01

65

An investigation on the cytotoxicity and caspase-mediated apoptotic effect of biologically synthesized silver nanoparticles using Podophyllum hexandrum on human cervical carcinoma cells.  

PubMed

Now-a-days synthesis and characterization of silver nanoparticles (AgNPs) through biological entity is quite interesting to employ AgNPs for various biomedical applications in general and treatment of cancer in particular. This paper presents the green synthesis of AgNPs using leaf extract of Podophyllum hexandrum Royle and optimized with various parameters such as pH, temperature, reaction time, volume of extract and metal ion concentration for synthesis of AgNPs. TEM, XRD and FTIR were adopted for characterization. The synthesized nanoparticles were found to be spherical shaped with average size of 14 nm. Effects of AgNPs were analyzed against human cervical carcinoma cells by MTT Assay, quantification of ROS, RT-PCR and western blotting techniques. The overall result indicates that AgNPs can selectively inhibit the cellular mechanism of HeLa by DNA damage and caspase mediated cell death. This biological procedure for synthesis of AgNPs and selective inhibition of cancerous cells gives an alternative avenue to treat human cancer effectively. PMID:23117153

Jeyaraj, Murugaraj; Rajesh, Manoharan; Arun, Renganathan; MubarakAli, Davoodbasha; Sathishkumar, Gnanasekar; Sivanandhan, Ganeshan; Dev, Gnanajothi Kapil; Manickavasagam, Markandan; Premkumar, Kumpati; Thajuddin, Nooruddin; Ganapathi, Andy

2013-02-01

66

Sonochemical synthesis of silver nanoparticles using starch: a comparison.  

PubMed

A novel approach was applied to synthesize silver nanoparticles using starch under sonication. Colloidal silver nanoparticles solution exhibited an increase of absorption from 420 to 440?nm with increase starch quantity. Transmission electron microscopy followed by selected area electron diffraction pattern analysis indicated the formation of spherical, polydispersed, amorphous, silver nanoparticles of diameter ranging from 23 to 97?nm with mean particle size of 45.6?nm. Selected area electron diffraction (SAED) confirmed partial crystalline and amorphous nature of silver nanoparticles. Silver nanoparticles synthesized in this manner can be used for synthesis of 2-aryl substituted benzimidazoles which have numerous biomedical applications. The optimized reaction conditions include 10?ml of 1?mM AgNO3, 25?mg starch, 11 pH range, and sonication for 20?min at room temperature. PMID:24587771

Kumar, Brajesh; Smita, Kumari; Cumbal, Luis; Debut, Alexis; Pathak, Ravinandan Nath

2014-01-01

67

Silver nanoparticles incorporated onto ordered mesoporous silica from Tollen's reagent  

NASA Astrophysics Data System (ADS)

Noble metal nanostructures supported on mesoporous silica are bridge between traditional silica adsorbents and modern catalysts. In this work the Ag/SBA-15 mesoporous materials were synthesized and characterized. Various forms of nanosilver supported on ordered mesoporous template have been successfully obtained via proposed procedures. In all synthesized materials, Tollen's reagent (diammine silver complex [Ag(NH3)2]+) was used as a silver source. Silver nanoparticles were prepared by reduction of ammoniacal silver complex by formaldehyde in the solution of stabilizer. After reduction, Ag nanoparticles could be deposited on SBA-15, or added during traditional synthesis of SBA-15 giving silver or silver chloride nanoparticles in the combination with porous silica. Silver nanostructures as nanoparticles or nanowires were also embedded onto the SBA-15 by incipient wetness impregnation of silver ions. Absorbed silver ions were next reduced under hydrogen at high temperature. There are many advantages of utilized ammoniacal silver complex as a silver source. Proposed method is capable to synthesis of various metal nanostructures with controlled composition and morphology. The silver ammonia complex is composed of two ions surrounding and protecting the central silver ion, so it is possible to obtain very small nanoparticles using simple approach without any functionalization of external and internal surface of SBA-15. This approach allows obtaining greatly small silver nanoparticles on SBA-15 (4 nm) or nanowires depending on the metal loading amount. Moreover, the colloidal silver solution prepared from Tollen's reagent, in the presence of triblock copolymer, remains stable for a long time. Reduction of Tollen's reagent to silver colloidal solution seems to be efficient, fast and interesting approach for the preparation of supported silver nanostructures Obtained samples were characterized by powder X-ray diffraction, small angle X-ray scattering (SAXS), UV-vis spectroscopy, transmission electron microscopy (TEM), nitrogen adsorption-desorption isotherms and photoacoustic spectroscopy (PAS).

Zienkiewicz-Strza?ka, M.; Pasieczna-Patkowska, S.; Kozak, M.; Pikus, S.

2013-02-01

68

Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles  

PubMed Central

A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed. The examined results confirmed that the in situ synthesized silver nanoparticles were evenly distributed on the surface of fibers. The inhibition zone test and the antibacterial rate demonstrated that the finished fabrics have an excellent antibacterial property against Staphylococcus aureus and Escherichia coli. Moreover, the nanosilver-treated silk fabrics were laundered 0, 5, 10, 20, and 50 times and still retained the exceptional antibacterial property. When the treated fabrics were washed 50 times, the antibacterial rate is more than 97.43% for S. aureus and 99.86% for E. coli. The excellent laundering durability may be attributed to the tight binding between silver nanoparticles and silk fibers through the in situ synthesis. This method provides an economic method to enhance the antibacterial capability of silk fabrics with good resistance to washings. PMID:24872803

2014-01-01

69

Synthesis of silver nanoparticles and antibacterial property of silk fabrics treated by silver nanoparticles  

NASA Astrophysics Data System (ADS)

A silver nanoparticle solution was prepared in one step by mixing AgNO3 and a multi-amino compound (RSD-NH2) solution under ambient condition. RSD-NH2 was in-house synthesized by methacrylate and polyethylene polyamine in methanol, which has abundant amino and imino groups. However, the characterization of silver nanoparticles indicated that these nanoparticles are easy to agglomerate in solution. Therefore, an in situ synthesis method of silver nanoparticles on the silk fabrics was developed. The examined results confirmed that the in situ synthesized silver nanoparticles were evenly distributed on the surface of fibers. The inhibition zone test and the antibacterial rate demonstrated that the finished fabrics have an excellent antibacterial property against Staphylococcus aureus and Escherichia coli. Moreover, the nanosilver-treated silk fabrics were laundered 0, 5, 10, 20, and 50 times and still retained the exceptional antibacterial property. When the treated fabrics were washed 50 times, the antibacterial rate is more than 97.43% for S. aureus and 99.86% for E. coli. The excellent laundering durability may be attributed to the tight binding between silver nanoparticles and silk fibers through the in situ synthesis. This method provides an economic method to enhance the antibacterial capability of silk fabrics with good resistance to washings.

Zhang, Guangyu; Liu, Yan; Gao, Xiaoliang; Chen, Yuyue

2014-05-01

70

Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439 nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14 nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons.

Bindhu, M. R.; Sathe, V.; Umadevi, M.

2013-11-01

71

Synthesis, characterization and SERS activity of biosynthesized silver nanoparticles.  

PubMed

Silver nanoparticles were rapidly synthesized using Moringa oleifera flower extract as the reducing agent shows surface plasmon resonance peak at 439nm. The size and shape of the nanoparticles controlled by varying the concentration of M. oleifera flower extract in the reaction medium. The synthesized silver nanoparticles were well-dispersed spherical nanoparticles with the average size of 14nm. The retinoic acid present in M. oleifera flower extract used as reducing agent and proteins was responsible for capping of the bioreduced silver nanoparticles. The obtained nanoparticle shows size-dependent SERS activity. The SERS spectrum indicates that the pyridine adsorbed on the silver surface in a stand-on orientation via its nitrogen lone pair electrons. PMID:23867642

Bindhu, M R; Sathe, V; Umadevi, M

2013-11-01

72

Synthesis of silver nanoparticles from Melia dubia leaf extract and their in vitro anticancer activity.  

PubMed

Silver nanoparticles have a significant role in the pharmaceutical science. Especially, silver nanoparticles synthesized by the plant extracts lead a significant role in biological activities such as antimicrobial, antioxidant and anticancer. Keeping this in mind, the present work investigation has been taken up with the synthesized silver nanoparticles using the plant extract of Melia dubia and it characterizes by using UV-visible, XRD and SEM-EDS. The effect of the silver nanoparticles on human breast cancer (KB) cell line has been tested. Silver nanoparticles showed remarkable cytotoxicity activity against KB cell line with evidence of high therapeutic index value are the results are discussed. PMID:24769382

Kathiravan, V; Ravi, S; Ashokkumar, S

2014-09-15

73

Synthesis of silver nanoparticles from Melia dubia leaf extract and their in vitro anticancer activity  

NASA Astrophysics Data System (ADS)

Silver nanoparticles have a significant role in the pharmaceutical science. Especially, silver nanoparticles synthesized by the plant extracts lead a significant role in biological activities such as antimicrobial, antioxidant and anticancer. Keeping this in mind, the present work investigation has been taken up with the synthesized silver nanoparticles using the plant extract of Melia dubia and it characterizes by using UV-visible, XRD and SEM-EDS. The effect of the silver nanoparticles on human breast cancer (KB) cell line has been tested. Silver nanoparticles showed remarkable cytotoxicity activity against KB cell line with evidence of high therapeutic index value are the results are discussed.

Kathiravan, V.; Ravi, S.; Ashokkumar, S.

2014-09-01

74

Optical and structural properties of radiolytically in situ synthesized silver nanoparticles stabilized by chitosan/poly(vinyl alcohol) blends  

NASA Astrophysics Data System (ADS)

In this study, the potential of chitosan/poly(vinyl alcohol) (CS/PVA) blends as capping agent for stabilization of Ag-nanoparticles (Ag NPs) during their in situ gamma irradiation induced synthesis was investigated. The UV-vis absorption spectra show the surface plasmon absorption band around 410 nm, which confirms the formation of Ag-nanoparticles. It was found that the composition of CS/PVA blend affected the size of the obtained Ag-nanoparticles, as well as the parameters such as density, molar concentration and effective surface area, calculated from the experimentally obtained UV-vis absorption spectra and spectra obtained by simulation according to the Mie theory. SEM micrograph and XRD measurement indicated a spherical morphology and face centered cubic crystal structure of Ag-nanoparticles, with diameter around 12 nm. The values of optical band gap energy between valence and conduction bands (Eg), calculated from the UV-vis absorption spectra, also show dependence on the blend composition for Ag-CS/PVA colloids as well as for Ag-CS/PVA nanocomposites.

Krsti?, Jelena; Spasojevi?, Jelena; Radosavljevi?, Aleksandra; Šiljegov?, Milorad; Ka?arevi?-Popovi?, Zorica

2014-03-01

75

Synthesis of silver nanoparticles with antibacterial activity using the lichen Parmotrema praesorediosum  

PubMed Central

Development of a green chemistry process for the synthesis of silver nanoparticles has become a focus of interest. This would offer numerous benefits, including ecofriendliness and compatibility for biomedical applications. Here we report the synthesis of silver nanoparticles from the reduction of silver nitrate and an aqueous extract of the lichen Parmotrema praesorediosum as a reductant as well as a stabilizer. The physical appearance of these silver nanoparticles was characterized using ultraviolet-visible spectroscopy, electron microscopy, energy-dispersive spectroscopy, and X-ray diffraction techniques. The results show that silver nanoparticles synthesized using P. praesorediosum have an average particle size of 19 nm with a cubic structure. The antibacterial activity of the synthesized silver nanoparticles was tested against eight micro-organisms using the disk diffusion method. The results reveal that silver nanoparticles synthesized using P. praesorediosum have potential antibacterial activity against Gram-negative bacteria. PMID:24379670

Mie, Ropisah; Samsudin, Mohd Wahid; Din, Laily B; Ahmad, Azizan; Ibrahim, Nazlina; Adnan, Siti Noor Adnalizawati

2014-01-01

76

Toxicity of silver nanoparticles in zebrafish models  

NASA Astrophysics Data System (ADS)

This study was initiated to enhance our insight on the health and environmental impact of silver nanoparticles (Ag-np). Using starch and bovine serum albumin (BSA) as capping agents, silver nanoparticles were synthesized to study their deleterious effects and distribution pattern in zebrafish embryos (Danio rerio). Toxicological endpoints like mortality, hatching, pericardial edema and heart rate were recorded. A concentration-dependent increase in mortality and hatching delay was observed in Ag-np treated embryos. Additionally, nanoparticle treatments resulted in concentration-dependent toxicity, typified by phenotypes that had abnormal body axes, twisted notochord, slow blood flow, pericardial edema and cardiac arrhythmia. Ag+ ions and stabilizing agents showed no significant defects in developing embryos. Transmission electron microscopy (TEM) of the embryos demonstrated that nanoparticles were distributed in the brain, heart, yolk and blood of embryos as evident from the electron-dispersive x-ray analysis (EDS). Furthermore, the acridine orange staining showed an increased apoptosis in Ag-np treated embryos. These results suggest that silver nanoparticles induce a dose-dependent toxicity in embryos, which hinders normal development.

Asharani, P. V.; Lian Wu, Yi; Gong, Zhiyuan; Valiyaveettil, Suresh

2008-06-01

77

Biosynthesis of silver nanoparticles using pink guava waste extract (PGWE)  

Microsoft Academic Search

Bio-inspired silver nanoparticles were synthesized with the aid of a novel, non-toxic, eco-friendly biological material namely, pink guava waste extract (PGWE). The pink guava waste extract will act as the reducing agent in reduction process in order to reduce the aqueous salt solutions of the silver nitrate. Moreover, economically, this process will also lower the cost of producing metal nanoparticles

Norashikin Ahmad Zamanhuri; Rasyidah Alrozi; Mohamed Syazwan Osman

2012-01-01

78

Cytotoxic effect of Green synthesized silver nanoparticles using Melia azedarach against in vitro HeLa cell lines and lymphoma mice model  

Microsoft Academic Search

This communication explains the biosynthesis of stable silver nanoparticles (AgNPs) from Melia azedarach and its cytotoxicity against in vitro HeLa cells and in vivo Dalton's ascites Lymphoma (DAL) mice model. The AgNPs synthesis was determined by UV- visible spectrum and it was further characterized by Scanning Electron Microscopy (SEM), Dynamic light Scattering (DLS) and X-Ray Diffraction (XRD) analysis. Zeta potential

Raman Sukirtha; Kandula Manasa Priyanka; Jacob Joe Antony; Soundararajan Kamalakkannan; Thangam Ramar; Gunasekaran Palani; Muthukalingan Krishnan; Shanmugam Achiraman

79

Development of nanostructured silver vanadates decorated with silver nanoparticles as a novel antibacterial agent  

NASA Astrophysics Data System (ADS)

In this work we report the synthesis, characterization and application of silver vanadate nanowires decorated with silver nanoparticles as a novel antibacterial agent. These hybrid materials were synthesized by a precipitation reaction of ammonium vanadate and silver nitrate followed by hydrothermal treatment. The silver vanadate nanowires have lengths of the order of microns and diameters around 60 nm. The silver nanoparticles decorating the nanowires present a diameter distribution varying from 1 to 20 nm. The influence of the pH of the reaction medium on the chemical structure and morphology of silver vanadates was studied and we found that synthesis performed at pH 5.5-6.0 led to silver vanadate nanowires with a higher morphological yield. The antimicrobial activity of these materials was evaluated against three strains of Staphylococcus aureus and very promising results were found. The minimum growth inhibiting concentration value against a MRSA strain was found to be ten folds lower than for the antibiotic oxacillin.

Holtz, R. D.; Souza Filho, A. G.; Brocchi, M.; Martins, D.; Durán, N.; Alves, O. L.

2010-05-01

80

Facile synthesis of anisotropic silver nanoparticles and their surface-enhanced Raman scattering properties  

NASA Astrophysics Data System (ADS)

In this work, polyvinylpyrrolidone(PVP)-capped silver nanoparticles were synthesized using ethylene glycol as solvent and reducing agent through a simple, one-pot solvothermal method at 160 °C. UV-vis spectroscopy, TEM and Raman spectra are used to characterize the PVP-capped silver nanoparticles. The results show that the formed silver nanoparticles are anisotropy with different size and morphology such as triangle, hexagon and pentagon. Moreover, the formation process of silver nanoparticles was discussed in detail. Furthermore, the formed silver nanoparticles displayed high surface-enhanced Raman scattering effects.

Zhang, Danhui; Yang, Houbo

2014-02-01

81

Antituberculous effect of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The in vitro experiment, involving 1164 strains of the tuberculosis mycobacteria, exhibited a potentiating effect of silver nanoparticles on known antituberculous preparations in respect of overcoming drug-resistance of the causative agent. The in vitro experiment, based on the model of resistant tuberculosis, was performed on 65 white mice. An evident antituberculous effect of the nanocomposite on the basis of silver nanoparticles and isoniazid was proved. Toxicological assessment of the of nanopreparations was carried out. The performed research scientifically establishes efficacy and safety of the nanocomposite application in combination therapy of patients suffering from drug-resistant tuberculosis.

Kreytsberg, G. N.; Gracheva, I. E.; Kibrik, B. S.; Golikov, I. V.

2011-04-01

82

Optimization of Biological Synthesis of Silver Nanoparticles using Fusarium oxysporum  

PubMed Central

Silver nanoparticles are increasingly used in various fields of biotechnology and applications in the medicine. Objectives of this study were optimization of production of silver nanoparticles using biotransformations by Fusarium oxysporum, and a further study on the location of nanoparticles synthesis in this microorganism. The reaction mixture contained the following ingredients (final concentrations): AgNO3 (1-10 mM) as the biotransformation substrate, biomass as the biocatalyst, glucose (560 mM) as the electron donor, and phosphate buffer (pH= 7, 100 mM). The samples were taken from the reaction mixtures at different times, and the absorbance (430 nm) of the colloidal suspensions of silver nanoparticles hydrosols was read freshly (without freezing) and immediately after dilution (1:40). SEM and TEM analyses were performed on selected samples. The presence of AgNO3 (0.1 mM) in the culture as enzyme inducer, and glucose (560 mM) as electron donor had positive effects on nanoparticle production. In SEM micrographs, silver nanoparticles were almost spherical, single (25-50 nm) or in aggregates (100 nm), attached to the surface of biomass. The reaction mixture was successfully optimized to increase the yield of silver nanoparticles production. More details of the location of nanoparticles production by this fungus were revealed, which support the hypothesis that silver nanoparticles are synthesized intracellularly and not extracellularly. PMID:24250635

Korbekandi, Hassan; Ashari, Zeynab; Iravani, Siavash; Abbasi, Sajjad

2013-01-01

83

Green synthesis of silver nanoparticles for the control of mosquito disease vectors  

Technology Transfer Automated Retrieval System (TEKTRAN)

A biological method was used to synthesize stable silver nanoparticles. The nanoparticles were tested as larvicides against Aedes aegypti, Anopheles stephensi, and Culex quinquefasciatus. Annona squamosa leaf broth (5%) reduced aqueous AgNO3 to stable silver nanoparticles with average particle siz...

84

Sulfidation of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Rapid development of nanotechnologies that exploit the properties of silver nanoparticles (Ag-NPs) raises questions concerning the impact of Ag on the environment. Ag-NPs are currently among the most widely used in the nanotechnology industry and the amount released into the environment is expected to increase along with production (1). When present in geochemical systems, Ag-NPs may undergo a variety of changes due to varying redox, pH, and chemical conditions. Expected changes range from surface modification (e.g., oxidation, sulfidation, chloridation etc.) to complete dissolution and re-precipitation. In this context, the focus of our work is on understanding the behavior of synthetic Ag-NPs with different particle sizes under varying conditions relevant to the environment. Sulfidation of Ag-NPs is of particular interest since it among the processes most likely to occur in aqueous systems, in particular under reducing conditions. Three sizes of Ag-NPs coated with polyvinyl pyrrolidone were produced using the polyol process (2) (7 ±1; 20 ±4, and 40 ±9 nm). Batch solutions containing the different Ag-NPs were subsequently reacted with Na2S solutions of different concentrations. The sulfidation process was followed step-wise for 24 hours and the corrosion products formed were characterized by electron microscopy (TEM/SEM), diffraction (XRD), and photo-electron spectroscopy (XPS). Surface charge (pHPZC) of the products formed during this process was also measured, as were changes in solubility and reactivity. Based on experimental observations we infer that the sulfidation process is the result of dissolution-precipitation and find that: (i) acanthite (Ag2S) is formed as a corrosion product; (ii) Ag-NPs aggregation increased with sulfidation rate; (iii) pHPZC increases with the rate of sulfidation; and (iv) the solubility of the corrosion products formed from sulfidation appears lower than that of non-sulfidated Ag-NPs. We observe size-dependent differences in the kinetics of sulfidation and in solubility behavior. The results of this type of fundamental study are important for predicting the behavior and fate of Ag-NPs in natural ecosystems. For example, aggregation caused by sulfidation may limit transport in porous media such as soils. Modification of surface charge during the sulfidation process may have an important impact on electrostatic interactions between Ag-NPs and charged phases such as natural organic matter. Finally, it is well known that Ag+ has a greater toxicity than metallic Ag (3) and the observed decrease in solubility of Ag-NPs after sulfidation may strongly impact the toxicity of silver in the environment. (1) www.nanotechproject.org (2) F. Fievet, J.P. Lagier, B. Blin, B. Beaudoin and M. Figlarz, Solid State Ionics 32/33, 198 (1989) (3) G.A. Sotiriou and S.E. Pratsinis, Environmental Science & Technology 14, 5649 (2010).

Levard, C.; Michel, F. M.; Brown, G. E.

2010-12-01

85

Synthesis, characterization and evaluation of silver nanoparticles through leaves of Abrus precatorius L.: an important medicinal plant  

NASA Astrophysics Data System (ADS)

Biologically synthesized nanoparticles have been widely used in the field of medicine. The present study reports the green synthesis of silver nanoparticles using Abrus precatorius leaf extract with silver nitrate solution as reducing agent. The synthesized silver nanoparticles were analyzed through UV-Visible spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, atomic force microscopy and Fourier transform infrared. The synthesized silver nanoparticles were disk shaped with an average size of 19 nm. These silver nanoparticles were evaluated for antibacterial activity. The diameter of inhibition zones around the disk of Pseudomonas aeruginosa and Staphylococcus aureus are resistant to silver nanoparticles, whereas Escherichia coli and Bacillus thuringiensis are susceptible when compared with the other two species. The results were compared with the ciprofloxacin-positive control and silver nitrate. It is concluded that the green synthesis of silver nanoparticles is very fast, easy, cost-effective and eco-friendly and without any side effects.

Gaddala, Bhumi; Nataru, Savithramma

2015-01-01

86

Coconut water assisted green synthesis of silver nanoparticles  

PubMed Central

Aim of the Study: The synthesis, characterization and application of biologically synthesized nanomaterials are an important aspect in nanotechnology. Materials and Methods: The present study deals with the synthesis of silver nanoparticles (Ag-NPs) using the coconut water (C. nucifera) as the reducing agent. The formation of Ag-NPs was characterized by UV-Visible Spectroscopy, Scanning Electron Microscopy (SEM), EDX, X-ray Diffraction (XRD) and FTIR spectroscopy. Results: The synthesized Ag-NPs were predominately polydispersed. Crystalline nature of the nanoparticle in the face centered cubic (fcc) structure are confirmed by the peaks in the XRD pattern corresponding to (111), (200), (220) and (311) planes. Fourier Transform Infra-Red (FT-IR) spectroscopy analysis showed that the synthesized nanoparicles was capped with bimolecular compounds which are responsible for the reduction of silver ions. Conclusion: The approach of green synthesis appears to be cost efficient, ecofriendly and easy alternative to conventional methods of silver nanoparticle synthesis. PMID:25400406

Elumalai, Erusan Kuppan; Kayalvizhi, Karuppsamy; Silvan, Simon

2014-01-01

87

Green synthesis of silver nanoparticles using Rhodobacter Sphaeroides  

Microsoft Academic Search

The use of microorganisms in the synthesis of nanoparticles emerges as an eco-friendly and exciting approach. In this study,\\u000a silver nanoparticles were successfully synthesized from AgNO3 by reduction of aqueous Ag+ ions with the cell filtrate of Rhodobacter sphaeroides. Nanoparticles were characterized by means of UV–vis absorption spectroscopy, X-Ray Diffraction (XRD), transmission electron\\u000a microscopy (TEM) and high-resolution transmission electron microscopy

Hong-Juan Bai; Bin-Sheng Yang; Chun-Jing Chai; Guan-E. Yang; Wan-Li Jia; Zhi-Ben Yi

88

Photosensitized synthesis of silver nanoparticles using Withania somnifera leaf powder and silver nitrate.  

PubMed

The metal nanoparticle synthesis is highly explored field of nanotechnology. The biological methods seem to be more effective; however, due to slow reduction rate and polydispersity of the resulting products, they are less preferred. In the present study, we report rapid and facile synthesis of silver nanoparticles at room temperature. The exposure of reaction mixtures containing silver nitrate and dried leaf powder of Withania somnifera Linn to direct sunlight resulted in reduction of metal ions within five minutes whereas, the dark exposure took almost 12h. Further studies using different light filters reveal the role of blue light in reduction of silver ions. The synthesized silver nanoparticles were characterized by UV-Vis, Infrared spectroscopy (IR), Transmission Electron Microscopy (TEM), X-ray Diffraction studies (XRD), Nanoparticle Tracking Analysis (NTA), Energy Dispersive Spectroscopy (EDS), and Cyclic Voltammetry (CV). The Antibacterial and antifungal studies showed significant activity as compared to their respective standards. PMID:24602813

Raut, Rajesh Warluji; Mendhulkar, Vijay Damodhar; Kashid, Sahebrao Balaso

2014-03-01

89

Silver Nanoparticles Part 2: BDo Silver Nanoparticles Inhibit Bacterial Growth?  

NSDL National Science Digital Library

The NACK Center is an organization committed to supporting two â??year degree programs in micro and nanotechnology. The center offers online educational material for curriculum enhancement in this subject field. One of these resources is a lab documentation focusing on the topic of silver nanoparticles. The lab "may be used with a middle school through high school biology class.â? The lesson includes objectives, sample solution preparations, and sample data and calculations. Overall, the objectives of this lesson are to practice aseptic techniques to inoculate/grow bacteria and describe the impact of silver nanoparticles on bacterial growth. The site requires a free log-in for access to the material.

90

Anti-Bacterial Properties of Silver Nanoparticles  

NSDL National Science Digital Library

This lesson from The Lawrence Hall of Science was taught in spring 2013 and focuses on synthesizing and testing silver nanoparticles. The three part lab involves "synthesis, testing and characterization and was implemented with a collaborative model." Each part of the lab is to be completed by a different class of students - those studying chemistry, biology, and engineering, respectively. This page includes links to Source Articles for the Hands-on Module, the Project Staff Write-up of the Hands-on Module, as well as a PowerPoint presentation and three documents detailing the labs.

91

Agricultural waste Annona squamosa peel extract: Biosynthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Development of reliable and eco-friendly process for the synthesis of metallic nanoparticles is an important step in the field of application of nanotechnology. We have developed modern method by using agriculture waste to synthesize silver nanoparticles by employing an aqueous peel extract of Annona squamosa in AgNO3. Controlled growth of silver nanoparticles was formed in 4 h at room temperature (25 °C) and 60 °C. AgNPs were irregular spherical in shape and the average particle size was about 35 ± 5 nm and it is consistent with particle size obtained by XRD Scherer equation.

Kumar, Rajendran; Roopan, Selvaraj Mohana; Prabhakarn, Arunachalam; Khanna, Venkatesan Gopiesh; Chakroborty, Subhendu

2012-05-01

92

Antibacterial activity of pH-dependent biosynthesized silver nanoparticles against clinical pathogen.  

PubMed

Simple, nontoxic, environmental friendly method is employed for the production of silver nanoparticles. In this study the synthesized nanoparticles UV absorption band occurred at 400 nm because of the surface Plasmon resonance of silver nanoparticles. The pH of the medium plays important role in the synthesis of control shaped and sized nanoparticles. The colour intensity of the aqueous solution varied with pH. In this study, at pH 9, the colour of the aqueous solution was dark brown, whereas in pH 5 the colour was yellowish brown; the colour difference in the aqueous solution occurred due to the higher production of silver nanoparticles. The antibacterial activity of biosynthesized silver nanoparticles was carried out against E. coli. The silver nanoparticles synthesized at pH 9 showed maximum antibacterial activity at 50 ?L. PMID:24967396

Chitra, Kethirabalan; Annadurai, Gurusamy

2014-01-01

93

Antibacterial Activity of pH-Dependent Biosynthesized Silver Nanoparticles against Clinical Pathogen  

PubMed Central

Simple, nontoxic, environmental friendly method is employed for the production of silver nanoparticles. In this study the synthesized nanoparticles UV absorption band occurred at 400?nm because of the surface Plasmon resonance of silver nanoparticles. The pH of the medium plays important role in the synthesis of control shaped and sized nanoparticles. The colour intensity of the aqueous solution varied with pH. In this study, at pH 9, the colour of the aqueous solution was dark brown, whereas in pH 5 the colour was yellowish brown; the colour difference in the aqueous solution occurred due to the higher production of silver nanoparticles. The antibacterial activity of biosynthesized silver nanoparticles was carried out against E. coli. The silver nanoparticles synthesized at pH 9 showed maximum antibacterial activity at 50??L. PMID:24967396

Chitra, Kethirabalan; Annadurai, Gurusamy

2014-01-01

94

Development of antimicrobial water filtration hybrid material from bio source calcium carbonate and silver nanoparticles  

NASA Astrophysics Data System (ADS)

Biobased calcium carbonate and silver hybrid nanoparticles were synthesized using a simple mechanochemical milling technique. The XRD spectrum showed that the hybrid materials is composed of crystalline calcite and silver nanoparticles. The TEM results indicated that the silver nanoparticles are discrete, uncapped and well stabilized in the surface of the eggshell derived calcium carbonate particles. The silver nanoparticles are spherical in shape and 5-20 nm in size. The SEM studies indicated that the eggshells are in micron size with the silver nanoparticle embedded in their surface. The hybrid eggshell/silver nanocomposite exhibited superior inhibition of E. coli growth using the Kirby-Bauer discs diffusion assay and comparing the zone of inhibition around the filter paper disc impregnated with the hybrid particles against pristine silver nanoparticles.

Apalangya, Vitus; Rangari, Vijaya; Tiimob, Boniface; Jeelani, Shaik; Samuel, Temesgen

2014-03-01

95

Gold and silver nanoparticles from Trianthema decandra: synthesis, characterization, and antimicrobial properties  

PubMed Central

Background There is an increasing commercial demand for nanoparticles due to their wide applicability in various markets, including medicine, catalysis, electronics, chemistry, and energy. In this report, a simple and ecofriendly chemical reaction for the synthesis of gold and silver nanoparticles from Trianthema decandra (Aizoaceae) has been developed. Methods and results On treatment of aqueous solutions containing chloroauric acid or silver nitrate with root extract of T. decandra, stable gold or silver nanoparticles were rapidly formed. The kinetics of reduction of gold and silver ions during the reaction was analyzed by ultraviolet-visible spectroscopy. Field emission-scanning electron microscopy showed formation of gold nanoparticles in various shapes, including spherical, cubical, triangular, and hexagonal, while silver nanoparticles were spherical. The size of the gold nanoparticles was 33–65 nm and that of the silver nanoparticles was 36–74 nm. Energy dispersive x-ray and Fourier transform infrared spectroscopy confirmed the presence of metallic gold and metallic silver in the respective nanoparticles. The antimicrobial properties of the synthesized nanoparticles were analyzed using the Kirby-Bauer method. The results show varied susceptibility of microorganisms to the gold and silver nanoparticles. Conclusion It is believed that phytochemicals present in T. decandra extract reduce the silver and gold ions into metallic nanoparticles. This strategy reduces the cost of production and the environmental impact. The silver and gold nanoparticles formed showed strong activity against all microorganisms tested. PMID:23091381

Geethalakshmi, R; Sarada, DVL

2012-01-01

96

Bioinspired synthesis of highly stabilized silver nanoparticles using Ocimum tenuiflorum leaf extract and their antibacterial activity  

NASA Astrophysics Data System (ADS)

Biosynthesis of nanoparticles is under exploration due to wide biomedical applications and research interest in nanotechnology. We herein reports bioinspired synthesis of silver nanoparticles with the aid of novel, non toxic ecofriendly biological material namely Ocimum tenuiflorum leaf extract. It acts as reducing as well as stabilizing agent. An intense surface plasmon resonance band at ˜450 nm in the UV-visible spectrum clearly reveals the formation of silver nanoparticles. The photoluminescence spectrum was recorded to study excitation and emission. TEM and PSD by dynamic light scattering studies showed that size of silver nanoparticles to be in range 25-40 nm. Face centered cubic structure of silver nanoparticles are confirmed by SAED pattern. The charge on synthesized silver nanoparticles was determined by zeta potential. The colloidal solution of silver nanoparticles were found to exhibit high antibacterial activity against three different strains of bacteria Escherichia coli (Gram negative), Corney bacterium (gram positive), Bacillus substilus (spore forming).

Patil, Rupali S.; Kokate, Mangesh R.; Kolekar, Sanjay S.

2012-06-01

97

Green Synthesis of Silver Nanoparticles Using Neem Leaf (Azadirachta indica) Extract  

NASA Astrophysics Data System (ADS)

Silver nanoparticles were successfully synthesized using crude neem leaf (Azadirachta indica) extract at room temperature. The formation and crystallinity of synthesized silver nanoparticles was confirmed by X-Ray diffraction (XRD) pattern. The average size of these silver nanoparticles is about 20-50 nm as observed by Transmission electron microscopy (TEM) images. Optical absorption measurements were performed to determine band-edge energy gap of these silver nanoparticles. Photoluminescence (PL) studies were performed to emphasize its emission properties. The synthesized silver nanoparticles could have major applications in the area of nanoscale optoelectronics devices and biomedical engineering. Our synthesis method has advantage over other conventional chemical routes because it is cost effective & environmental compatibility.

Shukla, Vineet Kumar; Pandey, Shipra; Pandey, Avinash C.

2010-10-01

98

Silver-nanoparticle dispersion from the consolidation of Ag-attached silica colloid  

E-print Network

Silver-nanoparticle dispersion from the consolidation of Ag-attached silica colloid Tae-Gon Kima; accepted 16 January 2004) Silver nanoparticles dispersed in a silica matrix were made by the consolidation of a Ag-attached silica colloid, which was synthesized via the electrolysis of a pure Ag electrode

Park, Byungwoo

99

Genotoxicity of silver nanoparticles in Allium cepa  

Microsoft Academic Search

Potential health and environmental effects of nanoparticles need to be thoroughly assessed before their widespread commercialization. Though there are few studies on cytotoxicity of nanoparticles on mammalian and human cell lines, there are hardly any reports on genotoxic and cytotoxic behavior of nanoparticles in plant cells. This study aims to investigate cytotoxic and genotoxic impacts of silver nanoparticles using root

Mamta Kumari; A. Mukherjee; N. Chandrasekaran

2009-01-01

100

Biosynthesis, characterization and cytotoxic effect of plant mediated silver nanoparticles using Morinda citrifolia root extract.  

PubMed

Silver has been used since time to control bodily infection, prevent food spoilage and heal wounds by preventing infection. The present study aims at an environmental friendly method of synthesizing silver nanoparticles, from the root of Morinda citrifolia; without involving chemical agents associated with environmental toxicity. The obtained nanoparticles were characterized by UV-vis absorption spectroscopy with an intense surface plasmon resonance band at 413 nm clearly reveals the formation of silver nanoparticles. Fourier transmission infra red spectroscopy (FTIR) showed nanopartilces were capped with plant compounds. Field emission-scanning electron microscopy (FE-SEM) and Transmission electron microscopy (TEM) showed that the spherical nature of the silver nanoparticles with a size of 30-55 nm. The X-ray diffraction spectrum XRD pattern clearly indicates that the silver nanoparticles formed in the present synthesis were crystalline in nature. In addition these biologically synthesized nanoparticles were also proved to exhibit excellent cytotoxic effect on HeLa cell. PMID:23434694

Suman, T Y; Radhika Rajasree, S R; Kanchana, A; Elizabeth, S Beena

2013-06-01

101

Amorphous silicon coatings with silver nanoparticles  

NASA Astrophysics Data System (ADS)

We describe a plasma-ion sputtering technology for obtaining amorphous silicon coatings containing dispersed silver nanoparticles with average dimensions of 20-30 nm. Results of X-ray diffraction and electron-microscopic investigations of these coatings are presented, and a possible mechanism of silver nano-particle formation from 2- to 3-nm-sized nanoclusters is considered.

Tuleushev, Yu. Zh.; Volodin, V. N.; Zhakanbaev, E. A.; Zdorovets, M. V.

2013-11-01

102

Immobilization of silver nanoparticles on polyethylene terephthalate  

PubMed Central

Two different procedures of grafting with silver nanoparticles (AgNP) of polyethylene terephthalate (PET), activated by plasma treatment, are studied. In the first procedure, the PET foil was grafted with biphenyl-4,4?-dithiol and subsequently with silver nanoparticles. In the second one, the PET foil was grafted with silver nanoparticles previously coated with the same dithiol. X-ray photoelectron spectroscopy and electrokinetic analysis were used for characterization of the polymer surface at different modification steps. Silver nanoparticles were characterized by ultraviolet-visible spectroscopy and by transmission electron microscopy (TEM). The first procedure was found to be more effective. It was proved that the dithiol was chemically bonded to the surface of the plasma-activated PET and that it mediates subsequent grafting of the silver nanoparticles. AgNP previously coated by dithiol bonded to the PET surface much less. PMID:24994960

2014-01-01

103

Synthesis of gold and silver nanoparticles using leaf extract of Perilla frutescens--a biogenic approach.  

PubMed

The present investigation demonstrates a rapid biogenic approach for the synthesis of gold and silver nanoparticles using biologically active and medicinal important Perilla frutescens leaf extract as a reducing and stabilizing agent under ambient conditions. Gold and silver nanoparticles were first synthesized from Perilla frutescens leaf extract which was used as a vegetable and in traditional medicines for a long time in Korea, Japan, and China. The nanoparticles obtained were characterized by UV-vis spectroscopy, transmission electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. Surface plasmon resonance spectra of gold and silver nanoparticles were obtained at 540 and 430 nm and triangular and spherical shape respectively. TEM studies showed that the particle sizes of gold and silver nanoparticles ranges -50 nm and -40 nm respectively. X-ray diffraction studies confirm that the biosynthesized nanoparticles were crystalline gold and silver. Fourier transform infra-red spectroscopy revealed that biomolecules were involved in the synthesis and capping of the nanoparticles produced. XRD and EDX confirmed the formation of gold and silver nanoparticles. This is a simple, efficient and rapid method to synthesize gold and silver nanoparticles at room temperature without use of toxic chemicals. Obtained gold and silver nanoparticles can be used in various biomedical and biotechnological applications. PMID:24738399

Basavegowda, Nagaraj; Lee, Yong Rok

2014-06-01

104

Biosynthesis of silver nanoparticles: Elucidation of prospective mechanism and therapeutic potential.  

PubMed

The synthesis of silver nanoparticles (AgNPs) was accomplished using Syzygium cumini fruit extract at room temperature. Various techniques were used to characterize the newly synthesized silver nanoparticles and their size was determined to be 10-15nm. Important findings of this study were the identification of biomolecules responsible for the synthesis of silver nanoparticles and elucidate the mechanism of biosynthesis. Flavonoids present in S. cumini were mainly responsible for the reduction and the stabilization of nanoparticles. The antioxidant properties of AgNPs were evaluated using various assays. The nanoparticles were also found to destroy Dalton lymphoma cell lines under in vitro condition. Silver nanoparticles (100?g/mL) decreased the viability of Dalton lymphoma (DL) cell lines up to 50%. The studies describing the biosynthesis of silver nanoparticles by fruit extract followed by the investigation of synthesis mechanism and anti-cancer activities may be useful for nanobiotechnology research opening a new arena in this field. PMID:24267328

Mittal, Amit Kumar; Bhaumik, Jayeeta; Kumar, Sanjay; Banerjee, Uttam Chand

2014-02-01

105

Biomimetic synthesis of silver nanoparticles by Citrus limon (lemon) aqueous extract and theoretical prediction of particle size  

Microsoft Academic Search

In the present study, silver nanoparticles were rapidly synthesized at room temperature by treating silver ions with the Citrus limon (lemon) extract. The effect of various process parameters like the reductant concentration, mixing ratio of the reactants and the concentration of silver nitrate were studied in detail. In the standardized process, 10?2M silver nitrate solution was interacted for 4h with

T. C. Prathna; N. Chandrasekaran; Ashok M. Raichur; Amitava Mukherjee

2011-01-01

106

Photocurrent enhancement in polythiophene doped with silver nanoparticles  

NASA Astrophysics Data System (ADS)

We studied the spectral dependence of the influence of silver nanoparticles (Ag NPs) on the photoconductivity of poly(3-hexylthiophene) (P3HT) thin films. 7 ± 2 nm silver nanoparticles were synthesized by thermal decomposition of an organometallic silver salt in organic solvent. Optical properties of the mixture of P3HT and Ag NPs and thin films with various Ag content were investigated. Spectral dependences of the photocurrent were measured for the films cast on the top of interdigitated microelectrodes. Antibatic behavior of the photocurrent with respect to the absorption spectrum was observed. Results shows 40-150 times enhancement of the photocurrents, depending on the wavelength, in films doped with Ag NPs compared with the pristine films. The existing theories on the influence of metallic nanoparticles in the photoactive layer of organic solar cells are reviewed and discussed.

Szeremeta, Janusz; Nyk, Marcin; Samoc, Marek

2014-11-01

107

Silver nanoparticles -- allies or adversaries?  

PubMed

Nanoparticles (NP) are structures with at least one dimension of less than 100 nanometers (nm) and unique properties. Silver nanoparticles (AgNP), due to their bactericidal action, have found practical applications in medicine, cosmetics, textiles, electronics, and other fields. Nevertheless, their less advantageous properties which make AgNP potentially harmful to public health or the environment should also be taken into consideration. These nanoparticles are cyto- and genotoxic and accumulate in the environment, where their antibacterial properties may be disadvantageous for agriculture and waste management. The presented study reviews data concerning the biological effects of AgNP in mammalian cells in vitro: cellular uptake and excretion, localization in cellular compartments, cytotoxicity and genotoxicity. The mechanism of nanoparticle action consists on induction of the oxidative stress resulting in a further ROS generation, DNA damage and activation of signaling leading to various, cell type-specific pathways to inflammation, apoptotic or necrotic death. In order to assure a safe application of AgNP, further detailed studies are needed on the mechanisms of the action of AgNP on mammalian cells at the molecular level. PMID:23540211

Bart?omiejczyk, Teresa; Lankoff, Anna; Kruszewski, Marcin; Szumiel, Irena

2013-01-01

108

Hybrid nanocomposites containing carboxymethylcellulose and silver nanoparticles.  

PubMed

Silver nanoparticles have high temperature stability and low volatility, and at the nanoscale are known to be an effective antifungal and antimicrobial agent. The present investigation involves the synthesis of silver nanoparticle/carboxymethylcellulose nanocomposites. The nanoparticles synthesised in this study had sizes in the range of 100 and 40 nm. The nanocomposites formed by a combination of metallic nanoparticles and carboxymethylcellulose were characterised by contact angle measurements, solubility tests, thermal and mechanical analyses, and morphological images. Improvements in the hydrophobic properties were observed with inclusion of the nanoparticles in the nanocomposites, with the best results occurring after the addition of 40 nm nanoparticles in a carboxymethylcellulose matrix. The silver nanoparticles tend to occupy the empty spaces in the pores of the carboxymethylcellulose matrix, inducing the collapse of these pores and thereby improving the tensile and barrier properties of the film. PMID:23755626

de Moura, Márcia R; Aouada, Fauze A; Mattoso, Luiz H C; Zucolotto, Valtencir

2013-03-01

109

Fabrication of tunable grating with silver nanoparticles  

Microsoft Academic Search

A tunable grating was fabricated with silver nanoparticles in a gradient increase of nanoparticle size along the grating direction in this study. Owing to the gradual increment of the nanoparticle size, the first order diffraction efficiencies of incident light presented as a function of the impinging position of the probe beam. Via a probe of monochromatic light ranged from 450

Tung-Kai Liu; Wen-Chi Hung; Ming-Shan Tsai; Yong-Chang Tsao; I.-Min Jiang

2009-01-01

110

Influence of surfactant on the preparation of silver nanoparticles by polyol method  

NASA Astrophysics Data System (ADS)

In this study, silver nanoparticles were synthesized from silver nitrate via a polyol method in ambient atmosphere. In our synthesis route, polyvinylpyrrolidone (PVP) is used as both size controller and capping agent, ethylene glycol acts both as solvent and reducing agent. The obtained silver nanoparticles were characterized by ultraviolet-visible spectrophotometry which indicated the formation of nanoparticles. Investigation of Fourier transform infrared spectroscopy clearly demonstrated the coordination between silver nanoparticles and PVP. Transmission electron microscopy (TEM) contributed to the particle size analysis. The surface plasmon resonance peak in absorption spectra of silver colloidal solution showed absorption from 406 to 409 nm. The average size of the resulting silver nanoparticles was below 10 nm with a dependency on the PVP concentration.

Dung Dang, Thi My; Thu Tuyet Le, Thi; Fribourg-Blanc, Eric; Chien Dang, Mau

2012-09-01

111

Procedure optimization for green synthesis of silver nanoparticles by aqueous extract of Eucalyptus oleosa.  

PubMed

The present study is dealing with the green synthesis of silver nanoparticles using the aqueous extract of Eucalyptus oleosa as a green synthesis procedure without any catalyst, template or surfactant. Colloidal silver nanoparticles were synthesized by reacting aqueous AgNO3 with E. oleosa leaf extract at non-photomediated conditions. The significance of some synthesis conditions such as: silver nitrate concentration, concentration of the plant extract, time of synthesis reaction and temperature of plant extraction procedure on the particle size of synthesized silver particles was investigated and optimized. The participations of the studied factors in controlling the particle size of reduced silver were quantitatively evaluated via analysis of variance (ANOVA). The results of this investigation showed that silver nanoparticles could be synthesized by tuning significant parameters, while performing the synthesis procedure at optimum conditions leads to form silver nanoparticles with 21nm as averaged size. Ultraviolet-visible spectroscopy was used to monitor the development of silver nanoparticles formation. Meanwhile, produced silver nanoparticles were characterized by scanning electron microscopy, energy-dispersive X-ray, and FT-IR techniques. PMID:25456666

Pourmortazavi, Seied Mahdi; Taghdiri, Mehdi; Makari, Vajihe; Rahimi-Nasrabadi, Mehdi

2014-10-16

112

Procedure optimization for green synthesis of silver nanoparticles by aqueous extract of Eucalyptus oleosa  

NASA Astrophysics Data System (ADS)

The present study is dealing with the green synthesis of silver nanoparticles using the aqueous extract of Eucalyptus oleosa as a green synthesis procedure without any catalyst, template or surfactant. Colloidal silver nanoparticles were synthesized by reacting aqueous AgNO3 with E. oleosa leaf extract at non-photomediated conditions. The significance of some synthesis conditions such as: silver nitrate concentration, concentration of the plant extract, time of synthesis reaction and temperature of plant extraction procedure on the particle size of synthesized silver particles was investigated and optimized. The participations of the studied factors in controlling the particle size of reduced silver were quantitatively evaluated via analysis of variance (ANOVA). The results of this investigation showed that silver nanoparticles could be synthesized by tuning significant parameters, while performing the synthesis procedure at optimum conditions leads to form silver nanoparticles with 21 nm as averaged size. Ultraviolet-visible spectroscopy was used to monitor the development of silver nanoparticles formation. Meanwhile, produced silver nanoparticles were characterized by scanning electron microscopy, energy-dispersive X-ray, and FT-IR techniques.

Pourmortazavi, Seied Mahdi; Taghdiri, Mehdi; Makari, Vajihe; Rahimi-Nasrabadi, Mehdi

2015-02-01

113

Synthesis of anisotropic silver nanoparticles using novel strain, Bacillus flexus and its biomedical application.  

PubMed

Synthesis of metallic nanoparticles has attracted by bacterial based production and alternative to physical and chemical approaches. The present work was focused to nominate a bacterial strain for synthesis of potential silver nanoparticles. The target was achieved by screening of 127 isolates from silver mining wastes. A strain designated S-27 found to be a potential candidate for rapid synthesis of silver nanoparticles among tested microorganisms. It was subjected to molecular characterization by 16S rDNA sequence analysis. It was found that S-27 belonging to Bacillus flexus. Synthesis of silver nanoparticles was achieved by addition of culture supernatants with aqueous silver nitrate solution, immediately it turns to brown colour solution showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles by UV-vis spectroscopy. Various instrumentation techniques, such as AFM, FESEM, XRD and FTIR, were adopted to characterize the synthesized nanoparticles. Anisotropic nanoparticles, such as spherical and triangular shaped nanoparticles, have been synthesized and sizes were found to be 12 and 65 nm, respectively. It was stable in aqueous solution in five months period of storage at room temperature in the dark. Synthesized nanoparticles showed efficacy on antibacterial property against clinically isolated multi-drug resistant (MDR) microorganisms. It is suggested that biogenic synthesis of nanoparticles have wide-application in medicine and physical chemistry and it can produce with eco-friendly, easy downstream processing and rapid scale-up processing. PMID:23018021

Priyadarshini, S; Gopinath, V; Meera Priyadharsshini, N; MubarakAli, D; Velusamy, P

2013-02-01

114

Biosynthesis of silver nanoparticles by a Bacillus sp. of marine origin  

NASA Astrophysics Data System (ADS)

This study was aimed to explore the nanoparticle synthesizing properties of a silver resistant Bacillus sp. isolated from a marine water sample. The 16SrDNA sequence analysis of the isolate proved it as a Bacillus strain. Very interestingly, the isolate was found to have the ability to form intracellular silver nanoparticles at room temperature within 24 hours. This was confirmed by the UV-Vis absorption analysis which showed a peak at 430 nm corresponding to the plasmon absorbance of silver nanoparticles. Further characterization of the nanoparticles was carried out by transmission electron microscopy (TEM) and scanning electron microscopy (SEM) analysis. The presence of silver nanoparticles with the size less than 100 nm was confirmed. These particles were found to be extremely stable as confirmed by the TEM analysis after three months of purification. So, the current study is the demonstration of an efficient synthesis of stable silver nanoparticles by a marine Bacillus strain.

Janardhanan, A.; Roshmi, T.; Varghese, Rintu T.; Soniya, E. V.; Mathew, Jyothis; Radhakrishnan, E. K.

2013-04-01

115

Adding two active silver atoms on au25 nanoparticle.  

PubMed

Alloy nanoparticles with atomic monodispersity is of importance for some fundamental research (e.g., the investigation of active sites). However, the controlled preparation of alloy nanoparticles with atomic monodispersity has long been a major challenge. Herein, for the first time a unique method, antigalvanic reduction (AGR), is introduced to synthesize atomically monodisperse Au25Ag2(SC2H4Ph)18 in high yield (89%) within 2 min. Interestingly, the two silver atoms in Au25Ag2(SC2H4Ph)18 do not replace the gold atoms in the precursor particle Au25(SC2H4Ph)18 but collocate on Au25, which was supported by experimental and calculated results. Also, the two silver atoms are active to play roles in stabilizing the alloy nanoparticle, triggering the nanoparticle fluorescence and catalyzing the hydrolysis of 1,3-diphenylprop-2-ynyl acetate. PMID:25580617

Yao, Chuanhao; Chen, Jishi; Li, Man-Bo; Liu, Liren; Yang, Jinlong; Wu, Zhikun

2015-02-11

116

Distribution of silver in rats following 28 days of repeated oral exposure to silver nanoparticles or silver acetate  

PubMed Central

Background The study investigated the distribution of silver after 28 days repeated oral administration of silver nanoparticles (AgNPs) and silver acetate (AgAc) to rats. Oral administration is a relevant route of exposure because of the use of silver nanoparticles in products related to food and food contact materials. Results AgNPs were synthesized with a size distribution of 14 ± 4 nm in diameter (90% of the nanoparticle volume) and stabilized in aqueous suspension by the polymer polyvinylpyrrolidone (PVP). The AgNPs remained stable throughout the duration of the 28-day oral toxicity study in rats. The organ distribution pattern of silver following administration of AgNPs and AgAc was similar. However the absolute silver concentrations in tissues were lower following oral exposure to AgNPs. This was in agreement with an indication of a higher fecal excretion following administration of AgNPs. Besides the intestinal system, the largest silver concentrations were detected in the liver and kidneys. Silver was also found in the lungs and brain. Autometallographic (AMG) staining revealed a similar cellular localization of silver in ileum, liver, and kidney tissue in rats exposed to AgNPs or AgAc. Using transmission electron microscopy (TEM), nanosized granules were detected in the ileum of animals exposed to AgNPs or AgAc and were mainly located in the basal lamina of the ileal epithelium and in lysosomes of macrophages within the lamina propria. Using energy dispersive x-ray spectroscopy it was shown that the granules in lysosomes consisted of silver, selenium, and sulfur for both AgNP and AgAc exposed rats. The diameter of the deposited granules was in the same size range as that of the administered AgNPs. No silver granules were detected by TEM in the liver. Conclusions The results of the present study demonstrate that the organ distribution of silver was similar when AgNPs or AgAc were administered orally to rats. The presence of silver granules containing selenium and sulfur in the intestinal wall of rats exposed to either of the silver forms suggests a common mechanism of their formation. Additional studies however, are needed to gain further insight into the underlying mechanisms of the granule formation, and to clarify whether AgNPs dissolve in the gastrointestinal system and/or become absorbed and translocate as intact nanoparticles to organs and tissues. PMID:21631937

2011-01-01

117

Nanosecond laser ablation of silver nanoparticle film  

NASA Astrophysics Data System (ADS)

Nanosecond laser ablation of polyvinylpyrrolidone (PVP) protected silver nanoparticle (20 nm diameter) film is studied using a frequency doubled Nd:YAG nanosecond laser (532 nm wavelength, 6 ns full width half maximum pulse width). In the sintered silver nanoparticle film, absorbed light energy conducts well through the sintered porous structure, resulting in ablation craters of a porous dome shape or crown shape depending on the irradiation fluence due to the sudden vaporization of the PVP. In the unsintered silver nanoparticle film, the ablation crater with a clean edge profile is formed and many coalesced nanoparticles of 50 to 100 nm in size are observed inside the ablation crater. These results and an order of magnitude analysis indicate that the absorbed thermal energy is confined within the nanoparticles, causing melting of nanoparticles and their coalescence to larger agglomerates, which are removed following melting and subsequent partial vaporization.

Chung, Jaewon; Han, Sewoon; Lee, Daeho; Ahn, Sanghoon; Grigoropoulos, Costas P.; Moon, Jooho; Ko, Seung H.

2013-02-01

118

Biogenic antimicrobial silver nanoparticles produced by fungi.  

PubMed

Aspergillus tubingensis and Bionectria ochroleuca showed excellent extracellular ability to synthesize silver nanoparticles (Ag NP), spherical in shape and 35?±?10 nm in size. Ag NP were characterized by transmission electron microscopy, X-ray diffraction analysis, and photon correlation spectroscopy for particle size and zeta potential. Proteins present in the fungal filtrate and in Ag NP dispersion were analyzed by electrophoresis (sodium dodecyl sulfate polyacrylamide gel electrophoresis). Ag NP showed pronounced antifungal activity against Candida sp, frequently occurring in hospital infections, with minimal inhibitory concentration in the range of 0.11-1.75 ?g/mL. Regarding antibacterial activity, nanoparticles produced by A. tubingensis were more effective compared to the other fungus, inhibiting 98.0 % of Pseudomonas. aeruginosa growth at 0.28 ?g/mL. A. tubingensis synthesized Ag NP with surprisingly high and positive surface potential, differing greatly from all known fungi. These data open the possibility of obtaining biogenic Ag NP with positive surface potential and new applications. PMID:22707055

Rodrigues, Alexandre G; Ping, Liu Yu; Marcato, Priscyla D; Alves, Oswaldo L; Silva, Maria C P; Ruiz, Rita C; Melo, Itamar S; Tasic, Ljubica; De Souza, Ana O

2013-01-01

119

Synthesis of silver nanoparticles by using tea leaf extract from Camellia Sinensis  

PubMed Central

The development of the biological synthesis of nanoparticles using microorganisms or plant extracts plays an important role in the field of nanotechnology as it is environmentally friendly and does not involve any harmful chemicals. In this study, the synthesis of silver nanoparticles using the leaves extract of Chinese tea from Camellia sinensis is reported. The synthesized nanoparticles were characterized using UV-vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. The XRD analysis shows that the synthesized silver nanoparticles are of face-centered cubic structure. Well-dispersed silver nanoparticles with an approximate size of 4 nm were observed in the TEM image. The application of the green synthesized nanoparticles can be used in many fields such as cosmetics, foods, and medicine. PMID:22904632

Loo, Yuet Ying; Chieng, Buong Woei; Nishibuchi, Mitsuaki; Radu, Son

2012-01-01

120

Biocide silver nanoparticles in two different silica-based coating  

NASA Astrophysics Data System (ADS)

Silica-based coatings containing biocide silver nanoparticles have been synthesized using low temperature sol-gel method. Two different silane based matrices, phenyltriethoxysilane (PhTEOS) and tetraethyl orthosilicate (TEOS), were selected as precursor to prepare silica-based film. The films were analyzed by using UV-visible spectrophotometry, atomic force microscopy (AFM) and scanning electron microscopy (SEM) for their optical, surface morphological as well as structural properties. Optical properties of nanosilver in these two matrices showed that the peak absorption observed at different wavelength, which is due to the fact that optical absorption of nanoparticles is affected by the surrounding medium. It is also found that the silver absorption has higher intensity in PhTEOS than in TEOS matrix, indicating higher concentration of silver nanoparticles being loaded into the coating. To study silver release property, the films were immersed in water for 12 and 20 days. AFM and SEM analyzes present that higher concentration of silver nanoparticles and smaller particle sizes were synthesis in PhTEOS coating and consequently, more particles remains on the surfaces after 20 days which leads to longer antibacterial activity of PhTEOS coating.

Babapour, A.; Yang, B.; Bahang, S.; Cao, W.

2012-09-01

121

Electrodeposited Silver Nanoparticles Patterned Hexagonally for SERS  

SciTech Connect

We have fabricated hexagonally patterned silver nanoparticles for surface-enhanced Raman scattering (SERS) by electrodepositing silver on the surface of an aluminum plate prepared by completely removing the oxide from anodic aluminum oxide (AAO) templates. Even after completely removing the oxide, well-ordered hexagonal patterns, similar to the shape of graphene, remained on the surface of the aluminum plate. The borders of the hexagonal pattern protruded up to form sorts of nano-mountains at both the sides and apexes of the hexagon, with the apexes protruding even more significantly than the sides. The aluminum plate prepared by completely removing the oxide has been used in the preparation of SERS substrates by sputter-coating of gold or silver on it. Instead of sputter-coating, here we have electro-deposited silver on the aluminum plate. When silver was electro-deposited on the plate, silver nanoparticles were made along the hexagonal margins.

Gu, Geun Hoi; Lee, Sue Yeone; Suh, Jung Sang [Nano-materials Laboratory, Department of Chemistry, Seoul National University, Kwanakgu, Kwanakro 599, Seoul 151-747 (Korea, Republic of)

2010-08-06

122

Cytotoxic Potential of Silver Nanoparticles  

PubMed Central

Silver nanoparticles (AgNPs) have been widely used in industrial, household, and healthcare-related products due to their excellent antimicrobial activity. With increased exposure of AgNPs to human beings, the risk of safety has attracted much attention from the public and scientists. In review of recent studies, we discuss the potential impact of AgNPs on individuals at the cell level. In detail, we highlight the main effects mediated by AgNPs on the cell, such as cell uptake and intracellular distribution, cytotoxicity, genotoxicity, and immunological responses, as well as some of the major factors that influence these effects in vivo and in vivo, such as dose, time, size, shape, surface chemistry, and cell type. At the end, we summarize the main influences on the cell and indicate the challenges in this field, which may be helpful for assessing the risk of AgNPs in future. PMID:24532494

Zhang, Tianlu; Wang, Liming

2014-01-01

123

Biological synthesis of very small silver nanoparticles by culture supernatant of Klebsiella pneumonia: The effects of visible-light irradiation and the liquid mixing process  

SciTech Connect

This study has investigated different visible-light irradiation's effect on the formation of silver nanoparticles from silver nitrate using the culture supernatant of Klebsiella pneumonia. Our study shows that visible-light emission can significantly prompt the synthesis of silver nanoparticles. Also, the study experimentally investigated the liquid mixing process effect on silver nanoparticle synthesis by visible-light irradiation. This study successfully synthesized uniformly dispersed silver nanoparticles with a uniform size and shape in the range of 1-6 nm with an average size of 3 nm. Furthermore, the study investigated the mechanism of the reduction of silver ions by culture supernatant of K. pneumonia, and used X-ray diffraction to characterize silver chloride as an intermediate compound. Silver chloride was prepared synthetically and used as a substrate for the synthesis of silver nanoparticles by culture supernatant of K. pneumonia. The silver nanoparticles have been prepared from silver chloride during this investigation for the first time.

Mokhtari, Narges [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Daneshpajouh, Shahram; Seyedbagheri, Seyedali; Atashdehghan, Reza [Hydrometallurgy Research Unit, Research and Development Center, National Iranian Copper Industries Company, Sarcheshmeh, Rafsanjan (Iran, Islamic Republic of); Abdi, Khosro [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Sarkar, Saeed [Research Center for Science and Technology in Medicine, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Minaian, Sara [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Shahverdi, Hamid Reza [Department of Material Science, Faculty of Engineering, Tarbiat Modares University, Tehran (Iran, Islamic Republic of); Shahverdi, Ahmad Reza, E-mail: shahverd@sina.tums.ac.ir [Department of Pharmaceutical Biotechnology and Biotechnology Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of)

2009-06-03

124

Green Synthesis of Robust, Biocompatible Silver Nanoparticles Using Garlic Extract  

PubMed Central

This paper details a facile approach for the synthesis of stable and monodisperse silver nanoparticles performed at ambient/low temperature where Allium sativum (garlic) extract functions as the silver salt reducing agent during nanoparticle synthesis as well as the post-synthesis stabilizing ligands. Varying the synthesis conditions provides control of particle size, size-distribution, and kinetics of particle formation. Infrared spectroscopy, energy dispersive x-ray chemical analysis, and high performance liquid chromatography indicated that the carbohydrates present in the garlic extract are the most likely nanoparticle stabilizing chemistry. The synthesized silver nanoparticles also demonstrate potential for biomeical applications, owing to the 1) enhanced stability in biological media, 2) resistance to oxidation by the addition of H2O2, 3) ease and scalability of synthesis, and 4) lack of harsh chemicals required for synthesis. Cytotoxicity assays indicated no decrease in cellular proliferation for vascular smooth muscle cells and 3T3 fibroblasts at a concentration of 25 ?g/ml, confirming that garlic extract prepared silver nanoparticles are ideal candidates for future experimentation and implementation into biomedical applications. PMID:24683414

Von White, Gregory; Kerscher, Petra; Brown, Ryan M.; Morella, Jacob D.; McAllister, William; Dean, Delphine; Kitchens, Christopher L.

2012-01-01

125

Biological Sciences SYNTHESIS AND CHARACTERIZATION OF SILVER NANOPARTICLES  

E-print Network

Silver nanoparticles exhibit new optical properties, which are observed neither in molecules nor in bulk metals. In the present study silver nanoparticle colloid was produced by chemical reduction method of silver salt (silver nitrate AgNO3) solution. The silver nanoparticles were characterized by using UV-VIS spectrometer and Scanning Electron Microscope (SEM). The Surface Plasmon Resonance peak in absorption spectra of silver colloidal solution showed an absorption maximum at 450 nm which indicated formation of silver nanoparticles. The size range 44nm to 56.55nm of silver nanoparticles was determined by using Scanning Electron Microscope (SEM). The absorbance range of prepared silver nanoparticles solution was checked on 1 st day, 5 th day, 18 th day and on 30 th day. There was no obvious change observed in peak position for 30 days, depicting the stability of Silver nanoparticles.

Basavaraj Udapudi; Praveenkumar Naik; Sabiha Tabassum Savadatti; Rupali Sharma; Samprita Balgi

126

Green synthesis and characterization of silver nanoparticles using alcoholic flower extract of Nyctanthes arbortristis and in vitro investigation of their antibacterial and cytotoxic activities.  

PubMed

Here we report the synthesis of silver nanoparticles using ethanolic flower extract of Nyctanthes arbortristis, UVvisible spectra and TEM indicated the successful formation of silver nanoparticles. Crystalline nature of the silver nanoparticles was confirmed by X-ray diffraction. Fourier Transform Infra-Red Spectroscopy analysis established the capping of the synthesized silver nanoparticles with phytochemicals naturally occurring in the ethanolic flower extract of N. arbortristis. The synthesized silver nanoparticles showed antibacterial activity against the pathogenic strain of Escherichia coli MTCC 443. Furthermore, cytotoxicity of the silver nanoparticles was tested on mouse fibroblastic cell line (L929) and found to be non-toxic, which thus proved their biocompatibility. Antibacterial activity and cytotoxicity assay carried out in this study open up an important perspective of the synthesized silver nanoparticles. PMID:25492011

Gogoi, Nayanmoni; Babu, Punuri Jayasekhar; Mahanta, Chandan; Bora, Utpal

2015-01-01

127

Synthesis and characterization of monodispersed silver nanoparticles  

NASA Astrophysics Data System (ADS)

Synthesis of silver nanoparticles (NPs) has become a fascinating and important field of applied chemical research. In this paper silver NPs were prepared using silver nitrate (AgNO3), gelatin, and cetyl trimethyl ammonium bromide (CTAB). The prepared silver NPs were exposed under the laser ablation. In our photochemical procedure, gelatin acts as a biopolymer and CTAB acts as a reducing agent. The appearance of surface plasmon band around 410 nm indicates the formation of silver NPs. The nature of the prepared silver NPs in the face-centered cubic (fcc) structure are confirmed by the peaks in the x-ray diffraction (XRD) pattern corresponding to (111), (200), (220) and (311) planes. Monodispersed, stable, spherical silver NPs with diameter about 10 nm were obtained and confirmed by high-resolution transmission electron microscope (HRTEM).

Jegatha Christy, A.; Umadevi, M.

2012-09-01

128

Effect of ionic liquid impurities on the synthesis of silver nanoparticles.  

PubMed

Imidazolium-based ionic liquids have been widely utilized as versatile solvents for metal nanoparticle synthesis; however, reactions to synthesize silver nanoparticles that are performed identically in different commercially obtained lots of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIM-BF(4)) give divergent results. This suggests that impurities in these nominally identical solvents play an important role in the resulting silver nanoparticle quality. To test the effect that impurities have on the quality of silver nanoparticles synthesized in BMIM-BF(4), silver nanoparticles were synthesized in carefully prepared and purified BMIM-BF(4) and compared against silver nanoparticles that were synthesized in the purified BMIM-BF(4) that had been spiked with trace amounts of water, chloride, and 1-methylimidazole. It was clearly demonstrated that trace amounts of these common ionic liquid impurities cause significant deviation in size and shape (creating polydisperse and irregularly shaped ensembles of both large and small particles), and also negatively impact the stabilization of the resulting silver nanoparticles. PMID:23092200

Lazarus, Laura L; Riche, Carson T; Malmstadt, Noah; Brutchey, Richard L

2012-11-13

129

Heteroaggregation of Silver Nanoparticles with Clay Minerals in Aqueous System  

NASA Astrophysics Data System (ADS)

Nanoparticles are increasingly being used in industrial processes and consumer products that exploit their beneficial properties and improve our daily lives. Nevertheless, they also attract attention when released into natural environment due to their potential for causing adverse effects. The fate and transport of nanoparticles in aqueous systems have been the focus of intense study. However, their interactions with other natural particles have received only limited attention. Clay minerals are ubiquitous in most aquatic systems and their variably charged surfaces can act as deposition sites that can alter the fate and transport of nanoparticles in natural aqueous environments. In this study, we investigated the homoaggregation of silver nanoparticles with different coating layers and their heteroaggregation behavior with clay minerals (illite, kaolinite, montmorillonite) in neutral pH solutions. Silver nanoparticles with a nominal diameter of 80 nm were synthesized with three different surface coating layers: uncoated, citrate-coated and Tween-coated. Illite (IMt-2), kaolinite (KGa-2), and montmorillonite (SWy-2) were purchased from the Clay Mineral Society (Indiana) and pretreated to obtain monocationic (Na-clay) and dicationic (Ca-clay) suspensions before the experiments. The change in hydrodynamic diameter as a function of time was monitored using dynamic light scattering (DLS) measurements in order to evaluate early stage aggregation as a function of electrolyte concentration in both the homo- and heteroaggregation scenarios. A shift in the critical coagulation concentration (CCC) values to lower electrolyte concentrations was observed in binary systems, compared to single silver nanoparticle and clay systems. The results also suggest more rapid aggregation in binary system during the early aggregation stage when compared to the single-particle systems. The behavior of citrate-coated silver nanoparticles was similar to that of the bare particles, while the Tween-coated silver nanoparticles showed high stability in both single and binary systems. There were no significant differences in early stage aggregation kinetics observed inthe Na-clay-nanoparticle or Ca-clay-nanoparticle systems, which suggested that the CCC values of the single Na- or Ca-clay suspensions depend only on the electrolyte concentration, not the original cations on the clay surface. These results provide a basic idea for understanding the heteroaggregation of different silver nanoparticles and clays, which can be utilized in further study of fate and transport of engineered nanoparticles in natural aqueous system.

Liu, J.; Burrow, E.; Hwang, Y.; Lenhart, J.

2013-12-01

130

Biosynthesis of iron and silver nanoparticles at room temperature using aqueous sorghum bran extracts.  

PubMed

Iron and silver nanoparticles were synthesized using a rapid, single step, and completely green biosynthetic method employing aqueous sorghum extracts as both the reducing and capping agent. Silver ions were rapidly reduced by the aqueous sorghum bran extracts, leading to the formation of highly crystalline silver nanoparticles with an average diameter of 10 nm. The diffraction peaks were indexed to the face-centered cubic (fcc) phase of silver. The absorption spectra of colloidal silver nanoparticles showed a surface plasmon resonance (SPR) peak centered at a wavelength of 390 nm. Amorphous iron nanoparticles with an average diameter of 50 nm were formed instantaneously under ambient conditions. The reactivity of iron nanoparticles was tested by the H(2)O(2)-catalyzed degradation of bromothymol blue as a model organic contaminant. PMID:21133391

Njagi, Eric C; Huang, Hui; Stafford, Lisa; Genuino, Homer; Galindo, Hugo M; Collins, John B; Hoag, George E; Suib, Steven L

2011-01-01

131

Plant-mediated biosynthesis of silver and gold nanoparticles.  

PubMed

Single-pot biosynthesis of silver and gold quasi-spherical nanoparticles (SNPs and GNPs) in the size range of 10-30 nm was attempted using Chenopodium album (an obnoxious weed). This method is rapid, facile, convenient and environmentally safe. Average crystal size was approximately 12 nm and 10 nm for silver and gold nanocrystals respectively. Synthesized NPs were stable in a wide range of pH as there was less variation in zeta potential values. In synthesis of SNPs and GNPs, naturally occurring oxalic acid played significant role in bio-reduction of silver nitrate and auric acid solution into their corresponding silver and gold nano-colloids in single step rapid process. PMID:21485852

Dwivedi, Amarendra Dhar; Gopal, Krishna

2011-02-01

132

Time-dependent effect in green synthesis of silver nanoparticles  

PubMed Central

The application of “green” chemistry rules to nanoscience and nanotechnology is very important in the preparation of various nanomaterials. In this work, we successfully developed an eco-friendly chemistry method for preparing silver nanoparticles (Ag-NPs) in natural polymeric media. The colloidal Ag-NPs were synthesized in an aqueous solution using silver nitrate, gelatin, and glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag-NPs were studied at different reaction times. The ultraviolet-visible (UV-vis) spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The prepared samples were also characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The use of eco-friendly reagents, such as gelatin and glucose, provides green and economic attributes to this work. PMID:21556342

Darroudi, Majid; Ahmad, Mansor Bin; Zamiri, Reza; Zak, AK; Abdullah, Abdul Halim; Ibrahim, Nor Azowa

2011-01-01

133

Time-dependent effect in green synthesis of silver nanoparticles.  

PubMed

The application of "green" chemistry rules to nanoscience and nanotechnology is very important in the preparation of various nanomaterials. In this work, we successfully developed an eco-friendly chemistry method for preparing silver nanoparticles (Ag-NPs) in natural polymeric media. The colloidal Ag-NPs were synthesized in an aqueous solution using silver nitrate, gelatin, and glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag-NPs were studied at different reaction times. The ultraviolet-visible (UV-vis) spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The prepared samples were also characterized by X-ray diffraction (XRD) and atomic force microscopy (AFM). The use of eco-friendly reagents, such as gelatin and glucose, provides green and economic attributes to this work. PMID:21556342

Darroudi, Majid; Ahmad, Mansor Bin; Zamiri, Reza; Zak, A K; Abdullah, Abdul Halim; Ibrahim, Nor Azowa

2011-01-01

134

Silver colloidal nanoparticles: antifungal effect against adhered cells and biofilms of Candida albicans and Candida glabrata  

Microsoft Academic Search

The aim of this study was to evaluate the effect of silver nanoparticles (SN) against Candida albicans and Candida glabrata adhered cells and biofilms. SN (average diameter 5 nm) were synthesized by silver nitrate reduction with sodium citrate and stabilized with ammonia. Minimal inhibitory concentration (MIC) tests were performed for C. albicans (n = 2) and C. glabrata (n = 2) grown in suspension

D. R. Monteiro; L. F. Gorup; S. Silva; M. Negri; E. R. de Camargo; R. Oliveira; D. B. Barbosa; M. Henriques

2011-01-01

135

Biosynthesis of silver nanoparticles using Moringa oleifera leaf extract and its application to optical limiting.  

PubMed

The Development of biologically inspired experimental processes for the synthesis of nanoparticles is evolving into an important branch of nanotechnology. The work presented here with the biosynthesis of silver nanoparticles using Moringa oleifera leaf extract as reducing and stabilizing agent and its application in nonlinear optics. The aqueous silver ions when exposed to Moringa oleifera leaf extract are reduced resulting in silver nanoparticles demonstrating the biosynthesis. The silver nanoparticles were characterized by UV-Visible, X-ray diffraction (XRD), Fourier transform infra-red spectroscopy (FT-IR) and transmission electron microscopy (TEM) techniques. TEM analysis shows a dispersion of the nanoparticles in a range of 5-80 nm with the average around 46 nm and are crystallized in face centred cubic symmetry. To show that these biosynthesized silver nanoparticles possess very good nonlinear properties similar to those nanoparticles synthesized by chemical route, we carried out the Z-scan studies with a 6 ns, 532 nm pulsed laser. We estimated the nonlinear absorption coefficient and compare it with the literature values of the nanoparticles synthesized through chemical route. The silver nanoparticles suspended in solution exhibited reverse saturable absorption with optical limiting threshold of 100 mJ/cm2. PMID:21449344

Sathyavathi, R; Krishna, M Bala Murali; Rao, D Narayana

2011-03-01

136

Biosynthesis of silver nanoparticles from Trichoderma species.  

PubMed

A total of 75 isolates belonging to five different species of Trichoderma viz., T. asperellum, T. harzianum, T. longibrachiatum, T. pseudokoningii and T. virens were screened for the production of silver nanoparticles. Although all the isolates produced nanoparticles, T. virens VN-11 could produce maximum nanoparticles as evident from the UV-Vis study. The highest Plasmon band was observed at 420 nm at every 24 h that attained maximum intensity at 120 h (0.543). The high resolution transmission electron microscopy (HRTEM) further provided the morphology of the nanoparticles. These nanoparticles were found single or aggregated with round and uniform in shape and 8-60 nm in size. The nitrate reductase activity of VN-11 was found to be 150 nmol/h/mL which confirmed the production of silver nanoparticles through reduction of Ag+ to Ag0. PMID:23898553

Devi, T Prameela; Kulanthaivel, S; Kamil, Deeba; Borah, Jyoti Lekha; Prabhakaran, N; Srinivasa, N

2013-07-01

137

Biosynthesis of silver nanoparticles from the marine seaweed Sargassum wightii and their antibacterial activity against some human pathogens  

NASA Astrophysics Data System (ADS)

In this paper, we have reported on biological synthesis of nano-sized silver and its antibacterial activity against human pathogens. The nanoparticles of silver were formed by the reduction of silver nitrate to aqueous silver metal ions during exposure to the extract of marine seaweed Sargassum wightii. The optical properties of the obtained silver nanoparticles were characterized using UV-visible absorption and room temperature photoluminescence. The X-ray diffraction results reveal that the synthesized silver nanoparticles are in the cubic phase. The existence of functional groups was identified using Fourier transform infrared spectroscopy. The morphology and size of the synthesized particles were studied with atomic force microscope and high-resolution transmission electron microscope measurements. The synthesized nanoparticles have an effective antibacterial activity against S. aureus, K. pneumoniae, and S. typhi.

Shanmugam, N.; Rajkamal, P.; Cholan, S.; Kannadasan, N.; Sathishkumar, K.; Viruthagiri, G.; Sundaramanickam, A.

2014-10-01

138

Light-driven transformation processes of anisotropic silver nanoparticles.  

PubMed

The photoinduced formation of silver nanoprisms from smaller silver seed particles in the presence of citrate anions is a classic example of a photomorphic reaction. In this case, light is used as a convenient tool to dynamically manipulate the shape of metal nanoparticles. To date, very little is known about the prevailing reaction mechanism of this type of photoreaction. Here we provide a detailed study of the shape transformation dynamics as a function of a range of different process parameters, such as photon energy and photon flux. For the first time, we provide direct evidence that the photochemical synthesis of silver nanoprisms from spherical seed nanoparticles proceeds via a light-activated two-dimensional coalescence mechanism. On the other hand, we could show that Ostwald ripening becomes the dominant reaction mechanism when larger silver nanoprisms are grown from photochemically synthesized smaller nanoprisms. This two-step reaction proceeds significantly faster and yields more uniform, sharper nanoprisms than the classical one-step photodevelopment process from seeds. The ability to dynamically control nanoparticle shapes and properties with light opens up novel synthesis avenues but also, more importantly, allows one to conceive new applications that exploit the nonstatic character of these nanoparticles and the ability to control and adjust their properties at will in a highly dynamic fashion. PMID:23730850

Lee, George P; Shi, Yichao; Lavoie, Ellen; Daeneke, Torben; Reineck, Philipp; Cappel, Ute B; Huang, David M; Bach, Udo

2013-07-23

139

Study of mechanism of enhanced antibacterial activity by green synthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The extensive use of silver nanoparticles needs a synthesis process that is greener without compromising their properties. The present study describes a novel green synthesis of silver nanoparticles using Guava (Psidium guajava) leaf extract. In order to compare with the conventionally synthesized ones, we also prepared Ag-NPs by chemical reduction. Their optical and morphological characteristics were thoroughly investigated and tested for their antibacterial properties on Escherichia coli. The green synthesized silver nanoparticles showed better antibacterial properties than their chemical counterparts even though there was not much difference between their morphologies. Fourier transform infrared (FTIR) spectroscopic analysis of the used extract and as-synthesized silver nanoparticles suggests the possible reduction of Ag + by the water-soluble ingredients of the guava leaf like tannins, eugenol and flavonoids. The possible reaction mechanism for the reduction of Ag + has been proposed and discussed. The time-dependent electron micrographs and the simulation studies indicated that a physical interaction between the silver nanoparticles and the bacterial cell membrane may be responsible for this effect. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is not just an environmentally viable technique but it also opens up scope to improve their antibacterial properties.

Parashar, Upendra Kumar; Kumar, Vinod; Bera, Tanmay; Saxena, Preeti S.; Nath, Gopal; Srivastava, Sunil K.; Giri, Rajiv; Srivastava, Anchal

2011-10-01

140

Study of mechanism of enhanced antibacterial activity by green synthesis of silver nanoparticles.  

PubMed

The extensive use of silver nanoparticles needs a synthesis process that is greener without compromising their properties. The present study describes a novel green synthesis of silver nanoparticles using Guava (Psidium guajava) leaf extract. In order to compare with the conventionally synthesized ones, we also prepared Ag-NPs by chemical reduction. Their optical and morphological characteristics were thoroughly investigated and tested for their antibacterial properties on Escherichia coli. The green synthesized silver nanoparticles showed better antibacterial properties than their chemical counterparts even though there was not much difference between their morphologies. Fourier transform infrared (FTIR) spectroscopic analysis of the used extract and as-synthesized silver nanoparticles suggests the possible reduction of Ag(+) by the water-soluble ingredients of the guava leaf like tannins, eugenol and flavonoids. The possible reaction mechanism for the reduction of Ag(+) has been proposed and discussed. The time-dependent electron micrographs and the simulation studies indicated that a physical interaction between the silver nanoparticles and the bacterial cell membrane may be responsible for this effect. Based on the findings, it seems very reasonable to believe that this greener way of synthesizing silver nanoparticles is not just an environmentally viable technique but it also opens up scope to improve their antibacterial properties. PMID:21918296

Parashar, Upendra Kumar; Kumar, Vinod; Bera, Tanmay; Saxena, Preeti S; Nath, Gopal; Srivastava, Sunil K; Giri, Rajiv; Srivastava, Anchal

2011-10-14

141

Biogenic synthesis of silver nanoparticles by leaf extract of Cassia angustifolia  

NASA Astrophysics Data System (ADS)

In this study Cassia angustifolia (senna) is used for the environmentally friendly synthesis of silver nanoparticles. Stable silver nanoparticles having symmetric surface plasmon resonance (SPR) band centred at 420 nm were obtained within 10 min at room temperature by treating aqueous solutions of silver nitrate with C. angustifolia leaf extract. The water soluble components from the leaves, probably the sennosides, served as both reducing and capping agents in the synthesis of silver nanoparticles. The nanoparticles were characterized using UV–Vis, Fourier transform infrared (FTIR) spectroscopic techniques and transmission electron microscopy (TEM). The nanoparticles were poly-dispersed, spherical in shape with particle size in the range 9–31 nm, the average size was found to be 21.6 nm at pH 11. The zeta potential was –36.4 mV and the particles were stable for 6 months. The crystalline phase of the nanoparticles was confirmed from the selected area diffraction pattern (SAED). The rate of formation and size of silver nanoparticles were pH dependent. Functional groups responsible for capping of silver nanoparticles were identified from the FTIR spectrum. The synthesized silver nanoparticles exhibited good antibacterial potential against Escherichia coli and Staphylococcus aureus.

Amaladhas, T. Peter; Sivagami, S.; Akkini Devi, T.; Ananthi, N.; Priya Velammal, S.

2012-12-01

142

Bacterial flagella as biotemplate for the synthesis of silver nanoparticle impregnated bionanomaterial  

NASA Astrophysics Data System (ADS)

The present study was carried out to synthesize one dimensional silver nanoparticle impregnated flagellar bionanomaterial. Flagella was isolated from Salmonella typhimurium and depolymerised into flagellin monomers. The flagellin monomers were repolymerised again into flagella using suitable technique. The molecular weight of native (NF) and polymerized flagella (PF) was determined using polyacrylamide gel electrophoresis. The NF and PF were used as a template, over which silver nanoparticles were impregnated using in situ chemical reduction process. The synthesized flagellar-silver nanoparticle bionanomaterials were characterized using UV-vis, FT-IR Raman and XRD spectroscopy, and High resolution transmission electron microscopy (HR-TEM). The characterization studies confirmed the attachment of silver nanoparticles over flagella and repolymerised flagella. The size of the silver nanoparticles on the flagella and repolymerised flagella varied and was in the range of 3-11 nm. I-V characteristics of the bionanomaterials were analyzed using Kethley meter which indicated the increase of conductivity after impregnation of silver nanoparticles. The results indicated that flagellar-silver nanoparticle bionanomaterials can be used as a potential one dimensional bionanomaterials for various applications.

Gopinathan, Priya; Ashok, Anuradha M.; Selvakumar, R.

2013-07-01

143

Colorimetric detection of pesticides based on calixarene modified silver nanoparticles in water  

NASA Astrophysics Data System (ADS)

Highly stable silver nanoparticles modified with p-sulfonatocalix[n]arene (n = 4, 8) were synthesized via a one-pot protocol in aqueous media and characterized by transmission electron microscopy, FT-IR and UV-vis spectroscopy. In comparison with p-sulfonatocalix[8]arene modified silver nanoparticles, p-sulfonatocalix[4]arene modified silver nanoparticles can be utilized as a novel colorimetric probe for optunal, allowing a rapid quantitative assay of optunal down to a concentration of 10-7 M, showing a great potential for application to real-time in situ detection of optunal. The possible mechanism is discussed.

Xiong, Dejun; Li, Haibing

2008-11-01

144

Biosynthesis of silver nanoparticles using citrus sinensis peel extract and its antibacterial activity  

NASA Astrophysics Data System (ADS)

Biosynthesis of silver nanoparticles (AgNPs) was achieved by a novel, simple green chemistry procedure using citrus sinensis peel extract as a reducing and a capping agent. The effect of temperature on the synthesis of silver nanoparticles was carried out at room temperature (25 °C) and 60 °C. The successful formation of silver nanoparticles has been confirmed by UV-vis, FTIR, XRD, EDAX, FESEM and TEM analysis and their antibacterial activity against Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and Staphylococcus aureus (Gram-positive) has been studied. The results suggest that the synthesized AgNPs act as an effective antibacterial agent.

Kaviya, S.; Santhanalakshmi, J.; Viswanathan, B.; Muthumary, J.; Srinivasan, K.

2011-08-01

145

Cytotoxicity and genotoxicity of biogenic silver nanoparticles  

NASA Astrophysics Data System (ADS)

Biogenic silver nanoparticles with 40.3 ± 3.5 nm size and negative surface charge (- 40 mV) were prepared with Fusarium oxysporum. The cytotoxicity of 3T3 cell and human lymphocyte were studied by a TaliTM image-based cytometer and the genotoxicity through Allium cepa and comet assay. The results of BioAg-w (washed) and BioAg-nw (unwashed) biogenic silver nanoparticles showed cytotoxicity exceeding 50 ?g/mL with no significant differences of response in 5 and 10 ?g/mL regarding viability. Results of genotoxicity at concentrations 5.0 and 10.0 ug/mL show some response, but at concentrations 0.5 and 1.0 ?g/mL the washed and unwashed silver nanoparticles did not present any effect. This in an important result since in tests with different bacteria species and strains, including resistant, MIC (minimal inhibitory concentration) had good answers at concentrations less than 1.9 ?g/mL. This work concludes that biogenic silver nanoparticles may be a promising option for antimicrobial use in the range where no cyto or genotoxic effect were observed. Furthermore, human cells were found to have a greater resistance to the toxic effects of silver nanoparticles in comparison with other cells.

Lima, R.; Feitosa, L. O.; Ballottin, D.; Marcato, P. D.; Tasic, L.; Durán, N.

2013-04-01

146

Structural and spectroscopic studies of thin film of silver nanoparticles  

NASA Astrophysics Data System (ADS)

We report the deposition of thin film of silver (Ag) nanoparticles by wet chemical method. The as-synthesized Ag nanoparticles have been characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), X-ray energy dispersive spectroscopy (EDS), field emission transmission electron microscopy (FETEM) and high-resolution TEM (HRTEM), UV-vis spectroscopy and thermogravimetric-differential thermal analysis (TG-DTA) respectively. FESEM image indicates that the silver film prepared on the quartz substrate is smooth and dense. XRD pattern reveals the face-centered cubic (fcc) structure of silver nanoparticles. EDS spectrum indicates that samples are nearly stoichiometric. From TEM analysis, it is found that the size of high purity Ag nanoparticles is ranging from 10 to 20 nm with slight agglomeration. Absorption in UV-vis region by these nanoparticles is characterized by the features reported in the literature, namely, a possible Plasmon peak at ˜403 nm. Optical absorbance spectra analysis reveals that the Ag film has an indirect band structure with bandgap energy 3.88 eV. TGA/DTA studies revealed that a considerable weight loss occurs between 175 and 275 °C; and the reaction is exothermic.

Khan, M. A. Majeed; Kumar, Sushil; Ahamed, Maqusood; Alrokayan, Salman A.; Alsalhi, M. S.; Alhoshan, Mansour; Aldwayyan, A. S.

2011-10-01

147

Piper nigrum Leaf and Stem Assisted Green Synthesis of Silver Nanoparticles and Evaluation of Its Antibacterial Activity Against Agricultural Plant Pathogens  

PubMed Central

Utilization of biological materials in synthesis of nanoparticles is one of the hottest topics in modern nanoscience and nanotechnology. In the present investigation, the silver nanoparticles were synthesized by using the leaf and stem extract of Piper nigrum. The synthesized nanoparticle was characterized by UV-vis spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray analysis (EDAX), and Fourier Transform Infrared Spectroscopy (FTIR). The observation of the peak at 460?nm in the UV-vis spectra for leaf- and stem-synthesized silver nanoparticles reveals the reduction of silver metal ions into silver nanoparticles. Further, XRD analysis has been carried out to confirm the crystalline nature of the synthesized silver nanoparticles. The TEM images show that the leaf- and stem-synthesized silver nanoparticles were within the size of about 7–50?nm and 9–30?nm, respectively. The FTIR analysis was performed to identify the possible functional groups involved in the synthesis of silver nanoparticles. Further, the antibacterial activity of the green-synthesized silver nanoparticles was examined against agricultural plant pathogens. The antibacterial property of silver nanoparticles is a beneficial application in the field of agricultural nanotechnology. PMID:24558336

Paulkumar, Kanniah; Gnanajobitha, Gnanadhas; Vanaja, Mahendran; Rajeshkumar, Shanmugam; Malarkodi, Chelladurai; Pandian, Kannaiyan; Annadurai, Gurusamy

2014-01-01

148

Optical limiting properties of silver nanoparticles fabricated by laser ablation  

NASA Astrophysics Data System (ADS)

Silver nanoparticles have been fabricated by laser ablation of a silver metal foil in solution. The presence of sodium bis(2-ethylhexyl) sulfosuccinate increases the yield of the nanoparticles and enhances their stability. The optical limiting performance of the silver nanoparticles embedded in a PMMA film is compared to that in an aqueous solution.

Ong, T. S.; Lee, S. S.; Van, L. H.; Hong, Ming Hui; Chong, Tow Chong

2004-10-01

149

Honey mediated green synthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The paper reports the pH controlled synthesis of silver nanoparticles using honey as reducing and stabilizing agents. By adjusting the pH of the aqueous solution containing metal ions and honey, nanoparticles of various size could be obtained at room temperature. The nanoparticles were characterized by UV-visible, high-resolution TEM, XRD and FTIR measurements. The colloid obtained at a pH of 8.5 is found to consist of monodispersed and nearly spherical silver nanoparticles of size ˜4 nm which is a significant advancement in biosynthesis. The high crystallinity with fcc phase is evidenced by clear lattice fringes in the high-resolution TEM image and peaks in the XRD pattern corresponding to (1 1 1), (2 0 0), (2 2 0), (3 1 1) and (2 2 2) planes. FTIR spectrum indicates that the nanoparticles are bound to protein through the carboxylate ion group.

Philip, Daizy

2010-03-01

150

Synthesis, characterization and optical properties of gelatin doped with silver nanoparticles  

NASA Astrophysics Data System (ADS)

In this study, silver nanoparticles were synthesized by chemical reduction of silver salt (AgNO3) solution. Formation of nanoparticles was confirmed by UV-visible spectrometry. The surface plasmon resonance peak is located at 430 nm. Doping of silver nanoparticles (Ag NPs) with gelatin biopolymer was studied. The silver content in the polymer matrix was in the range of 0.4-1 wt%. The formation of nanoparticles disappeared for silver content higher than 1 wt%. The morphology and interaction of gelatin doped with Ag NPs was examined by transmission electron microscopy and FTIR spectroscopy. The content of Ag NPs has a pronounced effect on optical and structural properties of gelatin. Optical parameters such as refractive index, complex dielectric constant were calculated. The dispersion of the refractive index was discussed in terms of the single - oscillator Wemple-DiDomenico model. Color properties of the prepared samples were discussed in the framework of CIE L*u*v* color space.

Mahmoud, K. H.; Abbo, M.

2013-12-01

151

Growth mechanism of silver nanowires synthesized by polyvinylpyrrolidone-assisted polyol reduction  

Microsoft Academic Search

Silver (Ag) nanowires with a pentagonal cross section have been synthesized by polyvinylpyrrolidone (PVP)-assisted polyol reduction in the presence of Pt nanoparticle seeds. The UV-visible absorption spectra and scanning electron microscopy have been used to trace the growth process of the Ag nanowires. X-ray photoelectron spectroscopy investigation further shows that the PVP molecules are adsorbed on the surface of the

Yan Gao; Peng Jiang; Li Song; Lifeng Liu; Xiaoqin Yan; Zhenping Zhou; Dongfang Liu; Jianxiong Wang; Huajun Yuan; Zengxing Zhang; Xiaowei Zhao; Xinyuan Dou; Weiya Zhou; Gang Wang; Sishen Xie

2005-01-01

152

Radiolytically induced formation and optical absorption spectra of colloidal silver nanoparticles in supercritical ethane  

Microsoft Academic Search

Colloidal silver nanoparticles were synthesized in supercritical ethane at 80 {sup o}C and 80-120 bar, with methanol as cosolvent. Solvated electrons, produced by a pulse of 20 MeV electrons, reduced the silver ions. The time-resolved technique of pulse radiolysis was employed to characterize the reduction products and colloidal metallic particles. The absorption spectra of small silver clusters (Agâ{sup +}, Agâ{sup

Nada M. Dimitrijevic; David M. Bartels; Charles D. Jonah; Kenji Takahashi; Tijana Rajh

2001-01-01

153

Mechanism of growth of colloidal silver nanoparticles stabilized by polyvinyl pyrrolidone in ?-irradiated silver nitrate solution  

Microsoft Academic Search

Silver nanoparticles were prepared by using polyvinyl pyrrolidone (PVP) as a stabilizer and ?-irradiation. Transmission electron microscopy (TEM) results showed that both the amount and the molecular weight of PVP in the irradiated solution considerably affect the average size of the silver nanoparticles. The average size of the silver nanoparticles decreases with increasing the amount of PVP in the solution,

Hyeon Suk Shin; Hyun Jung Yang; Seung Bin Kim; Mu Sang Lee

2004-01-01

154

Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity  

NASA Astrophysics Data System (ADS)

A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430 nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10 min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis.

Kumar, Deenadayalan Ashok; Palanichamy, V.; Roopan, Selvaraj Mohana

2014-06-01

155

Green synthesis of silver nanoparticles using Alternanthera dentata leaf extract at room temperature and their antimicrobial activity.  

PubMed

A green rapid biogenic synthesis of silver nanoparticles AgNPs using Alternanthera dentata (A. dentata) aqueous extract was demonstrated in this present study. The formation of silver nanoparticles was confirmed by Surface Plasmon Resonance (SPR) at 430nm using UV-visible spectrophotometer. The reduction of silver ions to silver nanoparticles by A. dentata extract was completed within 10min. Synthesized nanoparticles were characterized using UV-visible spectroscopy; Fourier transformed infrared spectroscopy (FT-IR), X-ray diffraction (XRD), scanning electron microscopy and transmission electron microscopy (TEM). The extracellular silver nanoparticles synthesis by aqueous leaf extract demonstrates rapid, simple and inexpensive method comparable to chemical and microbial methods. The colloidal solution of silver nanoparticles were found to exhibit antibacterial activity against Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumonia and, Enterococcus faecalis. PMID:24632169

Kumar, Deenadayalan Ashok; Palanichamy, V; Roopan, Selvaraj Mohana

2014-06-01

156

Chrysopogon zizanioides aqueous extract mediated synthesis, characterization of crystalline silver and gold nanoparticles for biomedical applications  

PubMed Central

The exploitation of various plant materials for the biosynthesis of nanoparticles is considered a green technology as it does not involve any harmful chemicals. The aim of this study was to develop a simple biological method for the synthesis of silver and gold nanoparticles using Chrysopogon zizanioides. To exploit various plant materials for the biosynthesis of nanoparticles was considered a green technology. An aqueous leaf extract of C. zizanioides was used to synthesize silver and gold nanoparticles by the bioreduction of silver nitrate (AgNO3) and chloroauric acid (HAuCl4) respectively. Water-soluble organics present in the plant materials were mainly responsible for reducing silver or gold ions to nanosized Ag or Au particles. The synthesized silver and gold nanoparticles were characterized by ultraviolet (UV)-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), Fourier transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) analysis. The kinetics decline reactions of aqueous silver/gold ion with the C. zizanioides crude extract were determined by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to the extract were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. This eco-friendly approach for the synthesis of nanoparticles is simple, can be scaled up for large-scale production with powerful bioactivity as demonstrated by the synthesized silver nanoparticles. The synthesized nanoparticles can have clinical use as antibacterial, antioxidant, as well as cytotoxic agents and can be used for biomedical applications. PMID:23861583

Arunachalam, Kantha D; Annamalai, Sathesh Kumar

2013-01-01

157

Green synthesis of silver nanoparticles using Calotropis gigantea and their potential mosquito larvicidal property  

Technology Transfer Automated Retrieval System (TEKTRAN)

In recent years the utilization of secondary metabolites from plant extract has emerged as a novel technology for the synthesis of nanoparticles. The aim of the present study was to evaluate the effect of plant synthesized silver nanoparticles (Ag NPs) using aqueous leaf extract of Calotropis gigan...

158

Glutathione promoted expeditious green synthesis of silver nanoparticles in water using microwaves  

EPA Science Inventory

Silver nanoparticles with size range 5-10 nm has been synthesized under microwave irradiation conditions using gluathione, an absolutely benign antioxidant that serves as the reducing as well as capping agent in aqueous medium. This rapid protocol yields the nanoparticles within ...

159

Effect of Accelerator in Green Synthesis of Silver Nanoparticles  

PubMed Central

Silver nanoparticles (Ag-NPs) were successfully synthesized in the natural polymeric matrix. Silver nitrate, gelatin, glucose, and sodium hydroxide have been used as silver precursor, stabilizer, reducing agent, and accelerator reagent, respectively. This study investigated the role of NaOH as the accelerator. The resultant products have been confirmed to be Ag-NPs using powder X-ray diffraction (PXRD), UV-vis spectroscopy, and transmission electron microscopy (TEM). The colloidal sols of Ag-NPs obtained at different volumes of NaOH show strong and different surface plasmon resonance (SPR) peaks, which can be explained from the TEM images of Ag-NPs and their particle size distribution. Compared with other synthetic methods, this work is green, rapid, and simple to use. The newly prepared Ag-NPs may have many potential applications in chemical and biological industries. PMID:21152307

Darroudi, Majid; Ahmad, Mansor Bin; Abdullah, Abdul Halim; Ibrahim, Nor Azowa; Shameli, Kamyar

2010-01-01

160

CTAB capped silver nanoparticles for plasmonic dye-sensitized solar cell  

NASA Astrophysics Data System (ADS)

To improve the light harvesting efficiency of Dye-sensitized solar cell (DSSC), we have explored the surface plasmon property of metal nanoparticles in this paper. Cetyl trimethylammonium bromide (CTAB) capped silver nanoparticles have been synthesized by wet chemical method and studied for spectroscopic and structural investigations. FTIR confirms the capping of CTAB on silver nanoparticles occurs via their head group. Williamson Hall plot revealed the presence of tensile strain. Finally, these particles have been incorporated in DSSC to study the plasmonic effect of nanoparticles on performance of DSSC.

Tanvi, Mahajan, Aman; Bedi, R. K.; Kumar, Subodh

2014-04-01

161

Biosynthesis of silver nanoparticles from Premna serratifolia L. leaf and its anticancer activity in CCl4-induced hepato-cancerous Swiss albino mice  

NASA Astrophysics Data System (ADS)

In this study, we report the biosynthesis of silver nanoparticles using the ethanolic leaf powder extract of Premna serratifolia L. and its anticancer activity in carbon tetra chloride (CCl4)-induced liver cancer in Swiss albino mice (Balb/c). The synthesized silver nanoparticles were characterized by SEM, FTIR and XRD analyses. The Debye-Scherrer equation was used to calculate particle size and the average size of silver nanoparticles synthesized from P. serratifolia leaf extract was 22.97 nm. The typical pattern revealed that the sample contained cubic structure of silver nanoparticles. FTIR analysis confirmed that the bioreduction of silver ions to silver nanoparticles is due to reduction by capping material of the plant extract. The silver nanoparticles of P. serratifolia leaf extract were effective in treating liver cancer in Swiss albino mice when compared with P. serratifolia leaf extract with isoleucine.

Arockia John Paul, J.; Karunai Selvi, B.; Karmegam, N.

2015-01-01

162

Biosynthesis, Antimicrobial and Cytotoxic Effect of Silver Nanoparticles Using a Novel Nocardiopsis sp. MBRC-1  

PubMed Central

The biosynthesis of nanoparticles has been proposed as a cost effective environmental friendly alternative to chemical and physical methods. Microbial synthesis of nanoparticles is under exploration due to wide biomedical applications, research interest in nanotechnology and microbial biotechnology. In the present study, an ecofriendly process for the synthesis of nanoparticles using a novel Nocardiopsis sp. MBRC-1 has been attempted. We used culture supernatant of Nocardiopsis sp. MBRC-1 for the simple and cost effective green synthesis of silver nanoparticles. The reduction of silver ions occurred when silver nitrate solution was treated with the Nocardiopsis sp. MBRC-1 culture supernatant at room temperature. The nanoparticles were characterized by UV-visible, TEM, FE-SEM, EDX, FTIR, and XRD spectroscopy. The nanoparticles exhibited an absorption peak around 420?nm, a characteristic surface plasmon resonance band of silver nanoparticles. They were spherical in shape with an average particle size of 45 ± 0.15?nm. The EDX analysis showed the presence of elemental silver signal in the synthesized nanoparticles. The FTIR analysis revealed that the protein component in the form of enzyme nitrate reductase produced by the isolate in the culture supernatant may be responsible for reduction and as capping agents. The XRD spectrum showed the characteristic Bragg peaks of 1 2 3, 2 0 4, 0 4 3, 1 4 4, and 3 1 1 facets of the face centered cubic silver nanoparticles and confirms that these nanoparticles are crystalline in nature. The prepared silver nanoparticles exhibited strong antimicrobial activity against bacteria and fungi. Cytotoxicity of biosynthesized AgNPs against in vitro human cervical cancer cell line (HeLa) showed a dose-response activity. IC50 value was found to be 200??g/mL of AgNPs against HeLa cancer cells. Further studies are needed to elucidate the toxicity and the mechanism involved with antimicrobial and anticancer activity of the synthesized AgNPs as nanomedicine. PMID:23936787

Manivasagan, Panchanathan; Senthilkumar, Kalimuthu; Sivakumar, Kannan; Kim, Se-Kwon

2013-01-01

163

Irradiation of silver and agar/silver nanoparticles with argon, oxygen glow discharge plasma, and mercury lamp.  

PubMed

The irradiation effect of argon, oxygen glow discharge plasma, and mercury lamp on silver and agar/silver nanoparticle samples is studied. The irradiation time dependence of the synthesized silver and agar/silver nanoparticle absorption spectra and their antibacterial effect are studied and compared. In the agar/silver nanoparticle sample, as the irradiation time of argon glow discharge plasma or mercury lamp increases, the peak intensity and the full width at half maximum, FWHM, of the surface plasmon resonance absorption band is increased, however a decrease of the peak intensity with oxygen glow plasma has been observed. In the silver nanoparticle sample, as the irradiation time of argon, oxygen glow discharge plasma or mercury lamp increases, the peak intensity of the surface plasmon resonance absorption band is increased, however, there is no significant change in the FWHM of the surface plasmon resonance absorption band. The SEM results for both samples showed nanoparticle formation with mean size about 50 nm and 40 nm respectively. Throughout the irradiation time with the argon, oxygen glow discharge plasma or mercury lamp, the antibacterial activity of several kinds of Gram-positive and Gram-negative bacteria has been examined. PMID:25184109

Ahmad, Mahmoud M; Abdel-Wahab, Essam A; El-Maaref, A A; Rawway, Mohammed; Shaaban, Essam R

2014-01-01

164

Green synthesis of colloidal silver nanoparticles using natural rubber latex extracted from Hevea brasiliensis  

NASA Astrophysics Data System (ADS)

Colloidal silver nanoparticles were synthesized by an easy green method using thermal treatment of aqueous solutions of silver nitrate and natural rubber latex (NRL) extracted from Hevea brasiliensis. The UV-Vis spectra detected the characteristic surface plasmonic absorption band around 435 nm. Both NRL and AgNO 3 contents in the reaction medium have influence in the Ag nanoparticles formation. Lower AgNO 3 concentration led to decreased particle size. The silver nanoparticles presented diameters ranging from 2 nm to 100 nm and had spherical shape. The selected area electron diffraction (SAED) patterns indicated that the silver nanoparticles have face centered cubic (fcc) crystalline structure. FTIR spectra suggest that reduction of the silver ions are facilitated by their interaction with the amine groups from ammonia, which is used for conservation of the NRL, whereas the stability of the particles results from cis-isoprene binding onto the surface of nanoparticles. Therefore natural rubber latex extracted from H. brasiliensis can be employed in the preparation of stable aqueous dispersions of silver nanoparticles acting as a dispersing and/or capping agent. Moreover, this work provides a new method for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive.

Guidelli, Eder José; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D.; Baffa, Oswaldo

2011-11-01

165

Extracellular biosynthesis of gold and silver nanoparticles using Krishna tulsi ( Ocimum sanctum) leaf  

NASA Astrophysics Data System (ADS)

Aqueous extract of Ocimum sanctum leaf is used as reducing agent for the environmentally friendly synthesis of gold and silver nanoparticles. The nanoparticles were characterized using UV-vis, transmission electron microscopy (TEM), X-ray diffraction (XRD) and FTIR analysis. These methods allow the synthesis of hexagonal gold nanoparticles having size ?30 nm showing two surface plasmon resonance (SPR) bands by changing the relative concentration of HAuCl 4 and the extract. Broadening of SPR is observed at larger quantities of the extract possibly due to biosorption of gold ions. Silver nanoparticles with size in the range 10-20 nm having symmetric SPR band centered around 409 nm are obtained for the colloid synthesized at room temperature at a pH of 8. Crystallinity of the nanoparticles is confirmed from the XRD pattern. Biomolecules responsible for capping are different in gold and silver nanoparticles as evidenced by the FTIR spectra.

Philip, Daizy; Unni, C.

2011-05-01

166

Antibacterial activity of silver bionanocomposites synthesized by chemical reduction route  

PubMed Central

Background The aim of this study is to investigate the functions of polymers and size of nanoparticles on the antibacterial activity of silver bionanocomposites (Ag BNCs). In this research, silver nanoparticles (Ag NPs) were incorporated into biodegradable polymers that are chitosan, gelatin and both polymers via chemical reduction method in solvent in order to produce Ag BNCs. Silver nitrate and sodium borohydride were employed as a metal precursor and reducing agent respectively. On the other hand, chitosan and gelatin were added as a polymeric matrix and stabilizer. The antibacterial activity of different sizes of silver nanoparticles was investigated against Gram-positive and Gram-negative bacteria by the disk diffusion method using Mueller-Hinton Agar. Results The properties of Ag BNCs were studied as a function of the polymer weight ratio in relation to the use of chitosan and gelatin. The morphology of the Ag BNCs films and the distribution of the Ag NPs were also characterized. The diameters of the Ag NPs were measured and their size is less than 20 nm. The antibacterial trait of silver/chitosan/gelatin bionanocomposites was investigated. The silver ions released from the Ag BNCs and their antibacterial activities were scrutinized. The antibacterial activities of the Ag BNC films were examined against Gram-negative bacteria (E. coli and P. aeruginosa) and Gram-positive (S. aureus and M. luteus) by diffusion method using Muller-Hinton agar. Conclusions The antibacterial activity of Ag NPs with size less than 20 nm was demonstrated and showed positive results against Gram-negative and Gram-positive bacteria. The Ag NPs stabilized well in the polymers matrix. PMID:22967920

2012-01-01

167

Memecylon edule leaf extract mediated green synthesis of silver and gold nanoparticles  

PubMed Central

We used an aqueous leaf extract of Memecylon edule (Melastomataceae) to synthesize silver and gold nanoparticles. To our knowledge, this is the first report where M. edule leaf broth was found to be a suitable plant source for the green synthesis of silver and gold nanoparticles. On treatment of aqueous solutions of silver nitrate and chloroauric acid with M. edule leaf extract, stable silver and gold nanoparticles were rapidly formed. The gold nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDAX) and Fourier transform infra-red spectroscopy (FTIR). The kinetics of reduction of aqueous silver and gold ions during reaction with the M. edule leaf broth were easily analyzed by UV-visible spectroscopy. SEM analysis showed that aqueous gold ions, when exposed to M. edule leaf broth, were reduced and resulted in the biosynthesis of gold nanoparticles in the size range 20–50 nm. TEM analysis of gold nanoparticles showed formation of triangular, circular, and hexagonal shapes in the size range 10–45 nm. The resulting silver nanoparticles were predominantly square with uniform size range 50–90 nm. EDAX results confirmed the presence of triangular nanoparticles in the adsorption peak of 2.30 keV. Further FTIR analysis was also done to identify the functional groups in silver and gold nanoparticles. The characterized nanoparticles of M. edule have potential for various medical and industrial applications. Saponin presence in aqueous extract of M. edule is responsible for the mass production of silver and gold nanoparticles. PMID:21753878

Elavazhagan, Tamizhamudu; Arunachalam, Kantha D

2011-01-01

168

Electrical properties of silver paste prepared from nanoparticles and lead-free frit.  

PubMed

Recently, PbO containing glass systems in commercial silver paste have been used due to their low glass transition temperature, good thermal and electrical properties. However, PbO is a hazardous material to both health and the environment. In this study, Pb-free silver paste was prepared by mixing commercial silver powder and silver nanoparticles. The commercial powder has an average particle size of 1.6 microm. The silver nanoparticles with particles size of 20-50 nm were synthesized by a chemical reduction method using surfactant. Pb-free frit was added into the mixed silver powder as the amounts of 3, 6 and 9 wt%. Using the obtained paste, thick films were fabricated by a screen printing on alumina substrate and the films were fired at temperature from 400 to 550 degrees C. The films had thickness of 6-11 microm and sheet resistivity of about 4-11 microomega cm. PMID:18047088

Park, Sung Hyun; Seo, Dong Seok; Lee, Jong Kook

2007-11-01

169

Extracellular biosynthesis of silver nanoparticles using the fungus Fusarium semitectum  

SciTech Connect

Development of environmental friendly procedures for the synthesis of metal nanoparticles through biological processes is evolving into an important branch of nanobiotechnology. In this paper, we report on the use of fungus 'Fusarium semitectum' for the extracellular synthesis of silver nanoparticles from silver nitrate solution (i.e. through the reduction of Ag{sup +} to Ag{sup 0}). Highly stable and crystalline silver nanoparticles are produced in solution by treating the filtrate of the fungus F. semitectum with the aqueous silver nitrate solution. The formations of nanoparticles are understood from the UV-vis and X-ray diffraction studies. Transmission electron microscopy of the silver particles indicated that they ranged in size from 10 to 60 nm and are mostly spherical in shape. Interestingly the colloidal suspensions of silver nanoparticles are stable for many weeks. Possible medicinal applications of these silver nanoparticles are envisaged.

Basavaraja, S.; Balaji, S.D. [Department of Materials Science, Gulbarga University, Gulbarga 585106, Karnataka (India); Department of Chemistry, Gulbarga University, Gulbarga 585106, Karnataka (India); Lagashetty, Arunkumar [Appa Institute of Engineering and Technology, Gulbarga 585102, Karnataka (India); Rajasab, A.H. [Department of Botany, Gulbarga University, Gulbarga 585106, Karnataka (India); Venkataraman, A. [Department of Materials Science, Gulbarga University, Gulbarga 585106, Karnataka (India); Department of Chemistry, Gulbarga University, Gulbarga 585106, Karnataka (India)], E-mail: raman_chem@rediffmail.com

2008-05-06

170

Synthesis of silver nanoparticles using reducing agents obtained from natural sources (Rumex hymenosepalus extracts)  

PubMed Central

We have synthesized silver nanoparticles from silver nitrate solutions using extracts of Rumex hymenosepalus, a plant widely found in a large region in North America, as reducing agent. This plant is known to be rich in antioxidant molecules which we use as reducing agents. Silver nanoparticles grow in a single-step method, at room temperature, and with no addition of external energy. The nanoparticles have been characterized by ultraviolet-visible spectroscopy and transmission electron microscopy, as a function of the ratio of silver ions to reducing agent molecules. The nanoparticle diameters are in the range of 2 to 40 nm. High-resolution transmission electron microscopy and fast Fourier transform analysis show that two kinds of crystal structures are obtained: face-centered cubic and hexagonal. PMID:23841946

2013-01-01

171

Facile Synthesis of Silver Nanoparticles Under {gamma}-Irradiation: Effect of Chitosan Concentration  

SciTech Connect

In the present study, a biopolymer, low molecular weight chitosan had been utilized as a 'green' stabilizing agent for the synthesis of silver nanoparticles under {gamma}-irradiation. The as-synthesized silver nanoparticles have particle diameters in the range of 5 nm-30 nm depending on the percentage of chitosan used (0.1 wt%, 0.5 wt%, 1.0 wt% and 2.0 wt%). It was found that the yield of the silver nanoparticles was in accordance with the concentration of chitosan presence in the solution due to the reduction by the chitosan radical during irradiation. The highly stable chitosan encapsulated silver nanoparticles were characterized using transmission electron microscopy (TEM), UV-Visible spectrophotometer (UV-VIS) and X-ray diffraction spectroscopy (XRD)

Huang, N. M.; Radiman, S.; Ahmad, A.; Idris, H. [Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi (Malaysia); Lim, H. N. [Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor (Malaysia); Khiew, P. S.; Chiu, W. S.; Tan, T. K. [Faculty of Engineering and Computer Science, Nottingham University, 43500 Semenyih (Malaysia)

2009-06-01

172

Luminescent and Raman Active Silver Nanoparticles with Polycrystalline Jie Zheng,*,,,  

E-print Network

to colloidal silver NPs prepared by typical solution-phase methods, of which only 2% of the particles emitLuminescent and Raman Active Silver Nanoparticles with Polycrystalline Structure Jie Zheng wavelength (0.5 nm for silver and gold), metal nanoparticles (NPs) often display strong single- electron

Wang, Zhong L.

173

Synthesis of gold nanoparticles and silver nanoparticles via green technology  

NASA Astrophysics Data System (ADS)

The proposed work describes the comparison of various methods of green synthesis for preparation of Gold and Silver nanoparticles. Pure extracts of Lemon (Citrus limon) and Tomato (Solanum lycopersicum) were mixed with aqueous solution of auric tetrachloride and silver nitrate. The resultant solutions were treated with four common techniques to assist in the reduction namely photo catalytic, thermal, microwave assisted reduction and solvo - thermal reduction. UV - Visible Spectroscopy results and STM images of the final solutions confirmed the formation of stable metallic nanoparticles. A preliminary account of the green synthesis work is presented here.

Ahmed, Zulfiqaar; Balu, S. S.

2012-11-01

174

Fabrication and characterization of silver nanoparticles using Delonix elata leaf broth  

NASA Astrophysics Data System (ADS)

The synthesis of nanoparticles from plant sources has proved to be an effective and alternative method for the novel production of nanoparticles. This paper reports the bioreduction of silver nitrate into silver nanoparticle by the leaf extract of Delonix elata. The synthesized silver nanoparticles were characterized by UV-visible (UV-vis) spectroscopy, Fourier infrared spectroscopy (FT-IR), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) coupled with Energy Dispersive Spectroscopy (EDS), high resolution transmission electron microscope (HRTEM). In addition the size of the NPs was calculated by using Malvern Zetasizer and the stability by zeta potential. UV-vis spectra show the surface plasmon resonance (SPR) at 432 nm. This reveals the reduction of silver ions (Ag+) into silver (Ag°) and indicating the formation of silver nanoparticles (AgNPs). SEM analysis revealed the spherical shape of the particles with sizes in the range of 35-45 nm and EDS spectrum confirmed the presence of silver along with other elements in the plant metabolite. The XRD analysis showed that the AgNPs are crystalline in nature and have face-centered cubic structure. FT-IR spectra show the existence of biomolecules responsible for the reduction of silver nitrate. The size of the AgNPs estimated from particle size distribution curve shows the 70 nm. The zeta potential of AgNPs was found to be -18 mV, indicating the dispersion and stability.

Sathiya, C. K.; Akilandeswari, S.

2014-07-01

175

Biosynthesis of Silver Nanoparticles from Desmodium triflorum: A Novel Approach Towards Weed Utilization  

PubMed Central

A single-step environmental friendly approach is employed to synthesize silver nanoparticles. The biomolecules found in plants induce the reduction of Ag+ ions from silver nitrate to silver nanoparticles (AgNPs). UV-visible spectrum of the aqueous medium containing silver ions demonstrated a peak at 425?nm corresponding to the plasmon absorbance of silver nanoparticles. Transmission electron microscopy (TEM) showed the formation of well-dispersed silver nanoparticles in the range of 5–20?nm. X-ray diffraction (XRD) spectrum of the AgNPs exhibited 2? values corresponding to the silver nanocrystal. The process of reduction is extracellular and fast which may lead to the development of easy biosynthesis of silver nanoparticles. Plants during glycolysis produce a large amount of H+ ions along with NAD which acts as a strong redoxing agent; this seems to be responsible for the formation of AgNPs. Water-soluble antioxidative agents like ascorbic acids further seem to be responsible for the reduction of AgNPs. These AgNPs produced show good antimicrobial activity against common pathogens. PMID:21350660

Ahmad, Naheed; Sharma, Seema; Singh, V. N.; Shamsi, S. F.; Fatma, Anjum; Mehta, B. R.

2011-01-01

176

Genotoxicity of silver nanoparticles in Allium cepa.  

PubMed

Potential health and environmental effects of nanoparticles need to be thoroughly assessed before their widespread commercialization. Though there are few studies on cytotoxicity of nanoparticles on mammalian and human cell lines, there are hardly any reports on genotoxic and cytotoxic behavior of nanoparticles in plant cells. This study aims to investigate cytotoxic and genotoxic impacts of silver nanoparticles using root tip cells of Allium cepa as an indicator organism. A.cepa root tip cells were treated with four different concentrations (25, 20, 75, and 100 ppm) of engineered silver nanoparticles (below 100 nm size) dispersion, to study endpoints like mitotic index, distribution of cells in mitotic phases, different types of chromosomal aberrations, disturbed metaphase, sticky chromosome, cell wall disintegration, and breaks. For each concentration five sets of microscopic observations were carried out. No chromosomal aberration was observed in the control (untreated onion root tips) and the mitotic index (MI) value was 60.3%. With increasing concentration of the nanoparticles decrease in the mitotic index was noticed (60.30% to 27.62%). The different cytological effects including the chromosomal aberrations were studied in detail for the treated cells as well as control. We infer from this study that silver nanoparticles could penetrate plant system and may impair stages of cell division causing chromatin bridge, stickiness, disturbed metaphase, multiple chromosomal breaks and cell disintegration. The findings also suggest that plants as an important component of the ecosystems need to be included when evaluating the overall toxicological impact of the nanoparticles in the environment. PMID:19616276

Kumari, Mamta; Mukherjee, A; Chandrasekaran, N

2009-09-15

177

Biosynthesis of silver and zinc oxide nanoparticles using Pichia fermentans JA2 and their antimicrobial property  

NASA Astrophysics Data System (ADS)

The development of eco-friendly alternative to chemical synthesis of metal nanoparticles is of great challenge among researchers. The present study aimed to investigate the biological synthesis, characterization, antimicrobial study and synergistic effect of silver and zinc oxide nanoparticles against clinical pathogens using Pichia fermentans JA2. The extracellular biosynthesis of silver and zinc oxide nanoparticles was investigated using Pichia fermentans JA2 isolated from spoiled fruit pulp bought in Vellore local market. The crystalline and stable metallic nanoparticles were characterized evolving several analytical techniques including UV-visible spectrophotometer, X-ray diffraction pattern analysis and FE-scanning electron microscope with EDX-analysis. The biosynthesized metallic nanoparticles were tested for their antimicrobial property against medically important Gram positive, Gram negative and fungal pathogenic microorganisms. Furthermore, the biosynthesized nanoparticles were also evaluated for their increased antimicrobial activities with various commercially available antibiotics against clinical pathogens. The biosynthesized silver nanoparticles inhibited most of the Gram negative clinical pathogens, whereas zinc oxide nanoparticles were able to inhibit only Pseudomonas aeruginosa. The combined effect of standard antibiotic disc and biosynthesized metallic nanoparticles enhanced the inhibitory effect against clinical pathogens. The biological synthesis of silver and zinc oxide nanoparticles is a novel and cost-effective approach over harmful chemical synthesis techniques. The metallic nanoparticles synthesized using Pichia fermentans JA2 possess potent inhibitory effect that offers valuable contribution to pharmaceutical associations.

Chauhan, Ritika; Reddy, Arpita; Abraham, Jayanthi

2015-01-01

178

Silver nanoparticles: Synthesis methods, bio-applications and properties.  

PubMed

Abstract Silver nanoparticles size makes wide range of new applications in various fields of industry. Synthesis of noble metal nanoparticles for applications such as catalysis, electronics, optics, environmental and biotechnology is an area of constant interest. Two main methods for Silver nanoparticles are the physical and chemical methods. The problem with these methods is absorption of toxic substances onto them. Green synthesis approaches overcome this limitation. Silver nanoparticles size makes wide range of new applications in various fields of industry. This article summarizes exclusively scalable techniques and focuses on strengths, respectively, limitations with respect to the biomedical applicability and regulatory requirements concerning silver nanoparticles. PMID:24937409

Abbasi, Elham; Milani, Morteza; Fekri Aval, Sedigheh; Kouhi, Mohammad; Akbarzadeh, Abolfazl; Tayefi Nasrabadi, Hamid; Nikasa, Parisa; Joo, San Woo; Hanifehpour, Younes; Nejati-Koshki, Kazem; Samiei, Mohammad

2014-06-17

179

Biodirected synthesis of Miconazole-conjugated bacterial silver nanoparticles and their application as antifungal agents and drug delivery vehicles.  

PubMed

The recent strategy to improve the efficacy of drugs is to combine them with metal nanoparticles for the control of microbial infections. Considering this fact, we developed a low cost and eco-friendly method for silver nanoparticles synthesis using the cell free supernatant of Delftia sp. strain KCM-006 and their application as antifungal agents and as a drug carrier. Transmission electron microscopy (TEM) and dynamic light scattering (DLS) analysis revealed the formation of spherical and monodispersed silver nanoparticles with an average size of 9.8nm. The synthesized nanoparticles were found to be photoluminescent, highly stable and crystalline in nature having a zeta potential of -31mV. The silver nanoparticles exhibited very good antifungal activity against various pathogenic Candida strains. Furthermore, the efficacy of nanoparticles was increased by conjugating the antifungal drug Miconazole to silver nanoparticles which exhibited significant fungicidal activity, inhibition of ergosterol biosynthesis and biofilm inhibition by increasing ROS levels. In addition, the cell viability and immunocytochemistry analysis against different normal cell lines including Chinese hamster ovary cells (CHO), human lung cell line (MRC5) and human vascular endothelial cells (HUVEC) demonstrated that these nanoparticles were non-toxic up to a concentration of 20?M. In conclusion, these results suggest that the synthesized nanoparticles find application as both antifungal agents and drug delivery vehicles. This is a first report on the preparation of silver nanoparticles using culture supernatant from Delftia sp. and also on the conjugation of Miconazole, an antifungal drug, to the bacterial silver nanoparticles. PMID:25460601

Kumar, C Ganesh; Poornachandra, Y

2015-01-01

180

Extracellular synthesis of silver nanoparticles by novel Pseudomonas veronii AS41G inhabiting Annona squamosa L. and their bactericidal activity  

NASA Astrophysics Data System (ADS)

In present investigation extracellular synthesis of silver nanoparticles were synthesized using cell free supernatant of Pseudomonas veronii AS41G isolated from Annona squamosa L. The bacterium significantly reduced silver nitrate to generate silver nanoparticles which was characterized with hyphenated techniques. Synthesis of silver nanoparticles preliminary confirmed by UV-Visible spectrophotometry with the intense peak at 410 nm, Further FTIR analysis revealed the possible role of biomolecules in the supernatant responsible for mediating the nanoparticles formation. The XRD spectra exhibited the characteristic Bragg peaks of 1 0 0, 1 1 1, 2 0 0, and 2 2 0 facets of the face centred cubic symmetry of nanoparticles suggesting that these nanoparticles were crystalline in nature. TEM microgram showed polydispersity of nanoparticles with size ranging from 5 to 50 nm. Synthesized silver nanoparticles showed antibacterial activity against human and environmental pathogens including MRSA. The study enlightens the role of biosynthesized silver nanoparticles as an emerging alternative for drug resistant microorganisms. The obtained results are promising enough to pave the environmentally benign nanoparticle synthesis processes without use of any toxic chemicals and also envision the emerging role of endophytes towards synthesis of nanoparticles. With scanty reports available on P.veronii species, a new role has been reported in this study which will be very valuable for future researchers working on it.

Baker, Syed; Mohan Kumar, K.; Santosh, P.; Rakshith, D.; Satish, S.

2015-02-01

181

Biogenesis of antibacterial silver nanoparticles using the endophytic bacterium Bacillus cereus isolated from Garcinia xanthochymus  

PubMed Central

Objective To synthesize the ecofriendly nanoparticles, which is viewed as an alternative to the chemical method which initiated the use of microbes like bacteria and fungi in their synthesis. Methods The current study uses the endophytic bacterium Bacillus cereus isolated from the Garcinia xanthochymus to synthesize the silver nanoparticles (AgNPs). The AgNPs were synthesized by reduction of silver nitrate solution by the endophytic bacterium after incubation for 3-5 d at room temperature. The synthesis was initially observed by colour change from pale white to brown which was confirmed by UV-Vis spectroscopy. The AgNPs were further characterized using FTIR, SEM-EDX and TEM analyses. Results The synthesized nanoparticles were found to be spherical with the size in the range of 20-40 nm which showed a slight aggregation. The energy-dispersive spectra of the nanoparticle dispersion confirmed the presence of elemental silver. The AgNPs were found to have antibacterial activity against a few pathogenic bacteria like Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Salmonella typhi and Klebsiella pneumoniae. Conclusions The endophytic bacteria identified as Bacillus cereus was able to synthesize silver nanoparticles with potential antibacterial activity. PMID:23593575

Sunkar, Swetha; Nachiyar, C Valli

2012-01-01

182

Biosynthesis and structural characterization of silver nanoparticles from bacterial isolates  

SciTech Connect

Graphical abstract: In this study five bacterial isolates belong to different genera were found to be able to biosynthesize silver nanoparticles. Biosynthesis and spectral characterization are reported here. Highlights: {yields} About 300 bacterial isolates were screened for their ability to produce nanosilvers {yields} Five of them were potential candidates for synthesis of silver nanoparticles {yields} Production of silver nanoparticles was examined using UV-Vis, XRD, SEM and EDS. {yields} The presence of nanoparticles with all five bacterial isolates was confirmed. -- Abstract: This study aimed to develop a green process for biosynthesis of silver nanomaterials by some Egyptian bacterial isolates. This target was achieved by screening an in-house culture collection consists of 300 bacterial isolates for silver nanoparticle formation. Through screening process, it was observed that strains belonging to Escherichia coli (S30, S78), Bacillus megaterium (S52), Acinetobacter sp. (S7) and Stenotrophomonas maltophilia (S54) were potential candidates for synthesis of silver nanoparticles. The extracellular production of silver nanoparticles by positive isolates was investigated by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). The results demonstrated that UV-visible spectrum of the aqueous medium containing silver ion showed a peak at 420 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy micrograph showed formation of silver nanoparticles in the range of 15-50 nm. XRD-spectrum of the silver nanoparticles exhibited 2{theta} values corresponding to the silver nanocrystal that produce in hexagonal and cubic crystal configurations with different plane of orientation. In addition, the signals of the silver atoms were observed by EDS-spectrum analysis that confirms the presence of silver nanoparticles (AgNPs) in all positive bacterial isolates.

Zaki, Sahar, E-mail: saharzaki@yahoo.com [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)] [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt); El Kady, M.F. [Fabrication Technology Department, Advanced Technology and New Materials Research Institute (ATNMRI), Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt)] [Fabrication Technology Department, Advanced Technology and New Materials Research Institute (ATNMRI), Mubarak City for Scientific Research and Technology Applications, Alexandria (Egypt); Abd-El-Haleem, Desouky [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)] [Environmental Biotechnology Department, Genetic Engineering and Biotechnology Research Institute, Mubarak City for Scientific Research and Technology Applications, Alexandria, 21934 New Burgelarab City (Egypt)

2011-10-15

183

Preparation and Characterization of Gelatin Nanofibers Containing Silver Nanoparticles  

PubMed Central

Ag nanoparticles (NPs) were synthesized in formic acid aqueous solutions through chemical reduction. Formic acid was used for a reducing agent of Ag precursor and solvent of gelatin. Silver acetate, silver tetrafluoroborate, silver nitrate, and silver phosphate were used as Ag precursors. Ag+ ions were reduced into Ag NPs by formic acid. The formation of Ag NPs was characterized by a UV-Vis spectrophotometer. Ag NPs were quickly generated within a few minutes in silver nitrate (AgNO3)/formic acid solution. As the water content of formic acid aqueous solution increased, more Ag NPs were generated, at a higher rate and with greater size. When gelatin was added to the AgNO3/formic acid solution, the Ag NPs were stabilized, resulting in smaller particles. Moreover, gelatin limits further aggregation of Ag NPs, which were effectively dispersed in solution. The amount of Ag NPs formed increased with increasing concentration of AgNO3 and aging time. Gelatin nanofibers containing Ag NPs were fabricated by electrospinning. The average diameters of gelatin nanofibers were 166.52 ± 32.72 nm, but these decreased with the addition of AgNO3. The average diameters of the Ag NPs in gelatin nanofibers ranged between 13 and 25 nm, which was confirmed by transmission electron microscopy (TEM). PMID:24758929

Jeong, Lim; Park, Won Ho

2014-01-01

184

Preparation, characterization and biocatalytic activity of a nanoconjugate of alpha amylase and silver nanoparticles.  

PubMed

The primary challenge in developing nanoparticle based enzymatic devices is to be able to chemically immobilize an enzyme, which will retain its activity or improve its function while being attached to the nanoparticle. This would be of even greater significance if the whole process could be performed under benign conditions without having to resort to functionalization of key molecules at various steps. In the present study the conjugates of amylase and silver nanoparticles were synthesized using neem leaf extract as the reducing and stabilizing agent. The silver nanoparticles were characterized using Surface Plasmon Resonance Spectra, Dynamic Light Spectroscopy (DLS), Fourier Transform Infrared Spectroscopy (FTIR), Circular Dichroism (CD) and Surface Tunneling Microscopy (STM). The silver nanoparticles retained 85% amylase activity. The nanobiocatalyst was further characterized in terms of kinetic parameters and thermal stability. It was thermally more stable as compared to the free alpha amylase enzyme. PMID:23901526

Mishra, Abhijeet; Ahmad, Razi; Singh, Veena; Gupta, Munishwar Nath; Sardar, Meryam

2013-07-01

185

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity.  

PubMed

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri. PMID:23103459

Bindhu, M R; Umadevi, M

2013-01-15

186

Synthesis of monodispersed silver nanoparticles using Hibiscus cannabinus leaf extract and its antimicrobial activity  

NASA Astrophysics Data System (ADS)

Synthesis of silver nanoparticles using leaf extract of Hibiscus cannabinus has been investigated. The influences of different concentration of H. cannabinus leaf extract, different metal ion concentration and different reaction time on the above cases on the synthesis of nanoparticles were evaluated. The synthesized nanoparticles were characterized using UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). The prepared silver nanoparticles were monodispersed, spherical in shape with the average particle size of 9 nm and shows surface plasmon peak at 446 nm. The study also reveals that the ascorbic acid present in H. cannabinus leaf extract has been used as reducing agent. The prepared silver nanoparticle shows good antimicrobial activity against Escherichia coli, Proteus mirabilis and Shigella flexneri.

Bindhu, M. R.; Umadevi, M.

2013-01-01

187

Optimization of Green Synthesis of Silver Nanoparticles from Leaf Extracts of Pimenta dioica (Allspice)  

PubMed Central

Production of silver nanoparticles from the leaf extracts of Pimenta dioica is reported for the first time in this paper. Three different sets of leaves were utilized for the synthesis of nanoparticles—fresh, hot-air oven dried, and sun-dried. These nanoparticles were characterized using UV-Vis spectroscopy and AFM. The results were diverse in that different sizes were seen for different leaf conditions. Nanoparticles synthesized using sun-dried leaves (produced using a particular ratio (1?:?0.5) of the leaf extract sample and silver nitrate (1?mM), resp.) possessed the smallest sizes. We believe that further optimization of the current green-synthesis method would help in the production of monodispersed silver nanoparticles having great potential in treating several diseases. PMID:24453836

Geetha, Akshay Rajeev

2013-01-01

188

Biosynthesis of silver nanoparticles using Alternanthera sessilis (Linn.) extract and their antimicrobial, antioxidant activities.  

PubMed

The present work focuses the use of the aqueous extract of Alternanthera sessilis Linn. (Amaranthaceae) in producing silver nanoparticles (AgNPs) from silver nitrate aqueous. Phytochemical analysis of the extract revealed the presence of alkaloid, tannins, ascorbic acid, carbohydrates and proteins and they serve as effective reducing and capping agents for converting silver nitrate into nanoparticles. The synthesized silver nanoparticles (AgNPs) were also tested for proteins and ascorbic acid. Its pH was also determined (5.63). The AgNPs obtained was characterized by UV-vis spectroscopy, FT-IR spectroscopy, SEM, Zeta sizer and TG-DSC. SEM images which revealed the presence of various shapes and sizes. FT-IR spectrum showed the AgNPs having a coating of proteins indicating a dual role of bio-molecules responsible for capping and efficient stabilization of the silver nanoparticles. Presence of impurities and melting point profile were screened by TG-DSC analyzer. AgNPs were synthesized from the silver nitrate through the reducing power of ascorbic acid present in A. sessilis leaves. In this study, we also investigated antimicrobial and antioxidant activity of green synthesized AgNPs. The antimicrobial activity is investigated by Bauer et al.'s method. Antioxidant activity was done by DPPH method. PMID:23006568

Niraimathi, K L; Sudha, V; Lavanya, R; Brindha, P

2013-02-01

189

Substrate independent silver nanoparticle based antibacterial coatings.  

PubMed

Infections arising from bacterial adhesion and colonization on medical device surfaces are a significant healthcare problem. Silver based antibacterial coatings have attracted a great deal of attention as a potential solution. This paper reports on the development of a silver nanoparticles based antibacterial surface that can be applied to any type of material surface. The silver nanoparticles were surface engineered with a monolayer of 2-mercaptosuccinic acid, which facilitates the immobilization of the nanoparticles to the solid surface, and also reduces the rate of oxidation of the nanoparticles, extending the lifetime of the coatings. The coatings had excellent antibacterial efficacy against three clinically significant pathogenic bacteria i.e. Staphylococcus epidermidis, Staphylococcus aureus and Pseudomonas aeruginosa. Studies with primary human fibroblast cells showed that the coatings had no cytotoxicity in vitro. Innate immune studies in cultures of primary macrophages demonstrated that the coatings do not significantly alter the level of expression of pro-inflammatory cytokines or the adhesion and viability of these cells. Collectively, these coatings have an optimal combination of properties that make them attractive for deposition on medical device surfaces such as wound dressings, catheters and implants. PMID:24630091

Taheri, Shima; Cavallaro, Alex; Christo, Susan N; Smith, Louise E; Majewski, Peter; Barton, Mary; Hayball, John D; Vasilev, Krasimir

2014-05-01

190

Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles  

EPA Science Inventory

Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxic...

191

Synergistic antibacterial effects of ?-lactam antibiotic combined with silver nanoparticles  

NASA Astrophysics Data System (ADS)

The bactericidal action of silver (0) nanoparticles and amoxicillin on Escherichia coli is studied, respectively. Increasing concentration of both amoxicillin (0-0.525 mg ml-1) and silver nanoparticles (0-40 µg ml-1) showed a higher antibacterial effect in Luria-Bertani (LB) medium. Escherichia coli cells have different bactericidal sensitivity to them. When amoxicillin and silver nanoparticles are combined, it results in greater bactericidal efficiency on Escherichia coli cells than when they were applied separately. Dynamic tests on bacterial growth indicated that exponential and stationary phases are greatly decreased and delayed in the synergistic effect of amoxicillin and silver nanoparticles. In addition, the effect induced by a preincubation with silver nanoparticles is examined. The results show that solutions with more silver nanoparticles have better antimicrobial effects. One hypothesized mechanism is proposed to explain this phenomenon.

Li, Ping; Li, Juan; Wu, Changzhu; Wu, Qingsheng; Li, Jian

2005-09-01

192

A versatile synthesis of highly bactericidal Myramistin® stabilized silver nanoparticles  

Microsoft Academic Search

Silver nanoparticles stabilized by a well-known antibacterial surfactant benzyldimethyl[3-(myristoylamino)propyl]ammonium chloride (Myramistin®) were produced for the first time by borohydride reduction of silver chloride sol in water. Stable aqueous dispersions of silver nanoparticles without evident precipitation for several months could be obtained. In vitro bactericidal tests showed that Myramistin® capped silver NPs exhibited notable activity against six different microorganisms---gram-positive and gram-negative

G. K. Vertelov; Yu A. Krutyakov; O. V. Efremenkova; A. Yu Olenin; G. V. Lisichkin

2008-01-01

193

A versatile synthesis of highly bactericidal Myramistin® stabilized silver nanoparticles  

Microsoft Academic Search

Silver nanoparticles stabilized by a well-known antibacterial surfactant benzyldimethyl[3-(myristoylamino)propyl]ammonium chloride (Myramistin®) were produced for the first time by borohydride reduction of silver chloride sol in water. Stable aqueous dispersions of silver nanoparticles without evident precipitation for several months could be obtained. In vitro bactericidal tests showed that Myramistin® capped silver NPs exhibited notable activity against six different microorganisms—gram-positive and gram-negative

G K Vertelov; Yu A Krutyakov; O V Efremenkova; A Yu Olenin; G V Lisichkin

2008-01-01

194

Catalytic degradation of methylene blue using biosynthesized gold and silver nanoparticles.  

PubMed

The scientific community is searching for new synthesis methods for the production of metallic nanoparticles. Green synthesis has now become a vast developing area of research. Here we report for the first time to best of our knowledge, a new green method for the synthesis of silver and gold nanoparticles using the Kashayam, Guggulutiktham, an ayurvedic medicine. This method is nontoxic and environmentally benign. The reduction and the stabilization capacity of the ayurvedic Kashayam are described in this paper. The size and shape of the silver and gold nanoparticles can be tuned by varying the quantity of the Kashayam. The synthesized nanoparticles are characterized using UV-VIS spectroscopy, TEM, XRD and FTIR. The size dependent catalytic activity of the synthesized nanoparticles is established in the reduction of Methylene Blue (MB) by NaBH4. PMID:24091344

Suvith, V S; Philip, Daizy

2014-01-24

195

Catalytic degradation of methylene blue using biosynthesized gold and silver nanoparticles  

NASA Astrophysics Data System (ADS)

The scientific community is searching for new synthesis methods for the production of metallic nanoparticles. Green synthesis has now become a vast developing area of research. Here we report for the first time to best of our knowledge, a new green method for the synthesis of silver and gold nanoparticles using the Kashayam, Guggulutiktham, an ayurvedic medicine. This method is nontoxic and environmentally benign. The reduction and the stabilization capacity of the ayurvedic Kashayam are described in this paper. The size and shape of the silver and gold nanoparticles can be tuned by varying the quantity of the Kashayam. The synthesized nanoparticles are characterized using UV-VIS spectroscopy, TEM, XRD and FTIR. The size dependent catalytic activity of the synthesized nanoparticles is established in the reduction of Methylene Blue (MB) by NaBH4.

Suvith, V. S.; Philip, Daizy

2014-01-01

196

The effect of silver ions and nanoparticles on biofilms and planktonic cultures of Nitrosomonas europaea.  

E-print Network

??Due to the effective antimicrobial properties of silver nanoparticles they represent a significant proportion of all consumer-?????related nanomaterials. The introduction of silver nanoparticles from these… (more)

Giska, Jonathan R., 1978-

2013-01-01

197

Magnetite and magnetite/silver core/shell nanoparticles with diluted magnet-like behavior  

SciTech Connect

In the present work is reported the use of the biopolymer chitosan as template for the preparation of magnetite and magnetite/silver core/shell nanoparticles systems, following a two step procedure of magnetite nanoparticles in situ precipitation and subsequent silver ions reduction. The crystalline and morphological characteristics of both magnetite and magnetite/silver core/shell nanoparticles systems were analyzed by high resolution transmission electron microscopy (HRTEM) and nanobeam diffraction patterns (NBD). The results of these studies corroborate the core/shell morphology and the crystalline structure of the magnetite core and the silver shell. Moreover, magnetization temperature dependent, M(T), measurements show an unusual diluted magnetic behavior attributed to the dilution of the magnetic ordering in the magnetite and magnetite/silver core/shell nanoparticles systems. - Graphical abstract: Biopolymer chitosan was used as stabilization media to synthesize both magnetite and magnetite/silver core/shell nanoparticles. Results of HRTEM and NBD patterns confirm core/shell morphology of the obtained nanoparticles. It was found that the composites show diluted magnet-like behavior.

Garza-Navarro, Marco [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Torres-Castro, Alejandro, E-mail: alejandro.torrescs@uanl.edu.m [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon 66600 (Mexico); Gonzalez, Virgilio; Ortiz, Ubaldo [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, Cd. Universitaria, San Nicolas de los Garza, Nuevo Leon 66450 (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon, Apodaca, Nuevo Leon 66600 (Mexico); De la Rosa, Elder [Centro de Investigaciones en Optica, A.P. 1-948, Leon Gto. 37160 (Mexico)

2010-01-15

198

Semiconductor quantum dots and metal nanoparticles: syntheses, optical properties, and biological applications  

Microsoft Academic Search

We review the syntheses, optical properties, and biological applications of cadmium selenide (CdSe) and cadmium selenide–zinc\\u000a sulfide (CdSe–ZnS) quantum dots (QDs) and gold (Au) and silver (Ag) nanoparticles (NPs). Specifically, we selected the syntheses\\u000a of QDs and Au and Ag NPs in aqueous and organic phases, size- and shape-dependent photoluminescence (PL) of QDs and plasmon\\u000a of metal NPs, and their

Vasudevanpillai Biju; Tamitake Itoh; Abdulaziz Anas; Athiyanathil Sujith; Mitsuru Ishikawa

2008-01-01

199

Antimicrobial efficacy and ocular cell toxicity from silver nanoparticles.  

PubMed

Silver in various forms has long been recognized for antimicrobial properties, both in biomedical devices and in eyes. However, soluble drugs used on the ocular surface are rapidly cleared through tear ducts and eventually ingested, resulting in decreased efficacy of the drug on its target tissue and potential concern for systemic side effects. Silver nanoparticles were studied as a source of anti-microbial silver for possible controlled-release contact lens controlled delivery formulations. Silver ion release over a period of several weeks from nanoparticle sources of various sizes and doses in vitro was evaluated in vitro against Pseudomonas aeruginosa strain PA01. Mammalian cell viability and cytokine expression in response to silver nanoparticle exposure is evaluated using corneal epithelial cells and eye-associated macrophages cultured in vitro in serum-free media. Minimal microcidal and cell toxic effects were observed for several silver nanoparticle suspensions and aqueous extraction times for bulk total silver concentrations commensurate with comparative silver ion (e.g., Ag(+) ((aq))) toxicity. This indicates that (1) silver particles themselves are not microcidal under conditions tested, and (2) insufficient silver ion is generated from these particles at these loadings to produce observable biological effects in these in vitro assays. If dosing allows substantially increased silver particle loading in the lens, the bactericidal efficacy of silver nanoparticles in vitro is one possible approach to limiting bacterial colonization problems associated with extended-wear contact lenses. PMID:19865601

Santoro, Colleen M; Duchsherer, Nicole L; Grainger, David W

2007-05-01

200

Synthesis of silver nanoparticles using medicinal Zizyphus xylopyrus bark extract  

NASA Astrophysics Data System (ADS)

In the present paper, biosynthesis of silver nanoparticles using Zizyphus xylopyrus bark extract is reported. Z. xylopyrus bark extract is efficiently used for the biosynthesis of silver nanoparticles. UV-Visible spectroscopy showed surface plasmon resonance peaks in the range 413-420 nm confirming the formation of silver nanoparticles. Different factors affecting the synthesis of silver nanoparticles like methodology for the preparation of extract, concentration of silver nitrate solution used for biosynthesis and initial pH of the reaction mixture were studied. The extract prepared with 10 mM AgNO3 solution by reflux extraction method at optimum initial pH of 11, resulted in higher conversion of silver ions to silver nanoparticles as compared with those prepared by open heating or ultrasonication. SEM analysis showed that the biosynthesized nanoparticles are spherical in nature and ranged from 60 to 70 nm in size. EDX suggested that the silver nanoparticles must be capped by the organic components present in the plant extract. This simple process for the biosynthesis of silver nanoparticles using aqueous extract of Z. xylopyrus is a green technology without the usage of hazardous and toxic solvents and chemicals and hence is environment friendly. The process has several advantages with reference to cost, compatibility for its application in medical and drug delivery, as well as for large-scale commercial production.

Sumi Maria, Babu; Devadiga, Aishwarya; Shetty Kodialbail, Vidya; Saidutta, M. B.

2014-11-01

201

Green synthesis, characterization and evaluation of biocompatibility of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Although green synthesis of silver nanoparticles (Ag NPs) by various plants and microorganisms has been reported, the potential of plants as biological materials for the synthesis of nanoparticles and their compatibility to biological systems is yet to be fully explored. In this study, we report a simple green method for the synthesis of Ag NPs using garlic clove extract as a reducing and stabilizing agent. In addition to green synthesis, biological response of Ag NPs in human lung epithelial A549 cells was also assessed. Ag NPs were rapidly synthesized using garlic clove extract and the formation of nanoparticles was observed within 30 min. The green synthesized Ag NPs were characterized using UV-vis spectrum, X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), X-ray energy-dispersive spectroscopy (EDX) and dynamic light scattering (DLS). Characterization data demonstrated that the particles were crystalline in nature and spherical shaped with an average diameter of 12 nm. Measurements of cell viability, cell membrane integrity and intracellular production of reactive oxygen species have shown that the green synthesized Ag NPs were nontoxic to human lung epithelial A549 cells. This study demonstrated a simple, cost-effective and environmentally benign synthesis of Ag NPs with excellent biocompatibility to human lung epithelial A549 cells. This preliminary in vitro investigation needs to be followed up by future studies with various biological systems.

Ahamed, Maqusood; Majeed Khan, M. A.; Siddiqui, M. K. J.; AlSalhi, Mohamad S.; Alrokayan, Salman A.

2011-04-01

202

Biosynthesis of silver nanoparticle from leaf extract of Desmodium gangeticum (L.) DC. and its biomedical potential  

NASA Astrophysics Data System (ADS)

An aqueous leaf extract of Desmodium gangeticum was employed to synthesize silver nano particles. Rapid formation of stable silver nanoparticles were observed on exposure of the aqueous leaf extract with solution of silver nitrate. The silver nanoparticles were characterized by UV-visible spectroscopy, scanning electron microscopy, energy dispersive X-ray analysis and transmission electron microscopy (TEM), and Fourier Transform Infra-Red spectroscopy (FTIR) UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), and Fourier Transform Infra-Red spectroscopy (FTIR). UV-visible spectrum of the aqueous medium peaked at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. SEM analysis revealed the spherical shape of the particles with sizes ranging from 18 to 39 nm and the EDAX spectrum confirmed the presence of silver along with other elements in the plant metabolite. Further, these biologically synthesized nanoparticles were found to be highly toxic against pathogenic bacteria Escherichia coli, thus implying significance of the present study in production of biomedical products.

Thirunavoukkarasu, M.; Balaji, U.; Behera, S.; Panda, P. K.; Mishra, B. K.

2013-12-01

203

Synthesis of silver nanoparticles by silver salt reduction and its characterization  

NASA Astrophysics Data System (ADS)

The wet chemical method route by metal salt reduction has been used to synthesize nanoparticles, using silver nitrate as an inorganic salt, aldehyde as a reducing agent and amino acid as a catalyst. During the reaction aldehyde oxidizes to carboxylic acid and encapsulates the silver nanoparticles to prevent agglomeration and provide barrier in the growth of particle. The existing work produces particles using lab grade chemical, here the presented work is by using industrial grade chemicals to make the process more cost & time effective. The nano silver powder has been studied for their formation, particle size, shape & compositional analysis using Scanning Electron Microscope (SEM) equipped with EDS. The particles size distributions were analyzed by Laser Particle Analyzer (LPA), structure & morphological analysis using x-ray diffraction (XRD) and Fourier-transform-infrared Spectroscopy (FTIR) confirmed the stabilization of particles by coating of carboxylic group. These studies infer that the particles are mostly spherical in shape and have an average size between 70 to 350 nm.

Muzamil, Muhammad; Khalid, Naveed; Danish Aziz, M.; Aun Abbas, S.

2014-06-01

204

Synthesis of Silver Nanoparticles Using Hydroxyl Functionalized Ionic Liquids and Their Antimicrobial Activity  

PubMed Central

We report a new one phase method for the synthesis of uniform monodisperse crystalline Ag nanoparticles in aqueous systems that has been developed by using newly synthesized mono and dihydroxylated ionic liquids and cationic surfactants based on 1,3-disubstituted imidazolium cations and halogens anions. The hydroxyl functionalized ionic liquids (HFILs) and hydroxyl functionalized cationic surfactants (HFCSs) also simultaneously acts both as the reductant and protective agent. By changing the carbon chain length, alcohol structure and anion of the 1,3-imidazolium based HFILs and HFCSs the particle size, uniform and dispersibility of nanoparticles in aqueous solvents could be controlled. Transmission electron microscopy (TEM), electron diffraction, UV-Vis and NMR, were used for characterization of HFILs, HFCSs and silver nanoparticles. TEM studies on the solution showed representative spherical silver nanoparticles with average sizes 2–8 nm, particularly 2.2 nm and 4.5 nm in size range and reasonable narrow particle size distributions (SD-standard distribution) 0.2 nm and 0.5 nm respectively. The all metal nanoparticles are single crystals with face centered cubic (fcc) structure. The silver nanoparticles surface of plasmon resonance band (?max) around 420 nm broadened and little moved to the long wavelength region that indicating the formation of silver nanoparticles dispersion with broad absorption around infrared (IR) region. Silver complexes of these HFILs as well as different silver nanoparticles dispersions have been tested in vitro against several gram positive and gram negative bacteria and fungus. The silver nanoparticles providing environmentally friendly and high antimicrobial activity agents. PMID:19325785

Dorjnamjin, Demberelnyamba; Ariunaa, Maamaa; Shim, Young Key

2008-01-01

205

Structural, optical and thermal properties of silver colloidal nanoparticles  

NASA Astrophysics Data System (ADS)

In this paper, colloidal silver nanoparticles were prepared by chemical reduction of AgNO3 and pure Sn in a new and simple method. The type of crystallite lattice and the size of nanopowders were estimated by X-Ray Diffraction (XRD) analysis. The geometric, heterogeneous and mixing structure of synthesized nanopowders were studied by Scanning Electron Microscopy (SEM). Optical properties such as plasmon absorption and frequency of soluble colloidal nanopowders in two solutions of distilled water and oil were investigated by UV-Visible spectroscopy, which was developed to calculate the absorbance spectra of nanoparticles solution containing a size distribution of particles using the Mie theory. Dipole and quadrupole plasmons related to molecular structure of water and oil were found by absorbance spectra. Also, Differential Scanning Calorimetry (DSC) analysis was used for determining the thermal behavior, endothermic and exothermic peaks of Ag nanopowder.

Naderi, S.; Ghaderi, A.; Solaymani, S.; Golzan, M. M.

2012-05-01

206

Structural and thermal studies of silver nanoparticles and electrical transport study of their thin films  

NASA Astrophysics Data System (ADS)

This work reports the preparation and characterization of silver nanoparticles synthesized through wet chemical solution method and of silver films deposited by dip-coating method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), field emission transmission electron microscopy (FETEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), and energy dispersive spectroscopy (EDX) have been used to characterize the prepared silver nanoparticles and thin film. The morphology and crystal structure of silver nanoparticles have been determined by FESEM, HRTEM, and FETEM. The average grain size of silver nanoparticles is found to be 17.5 nm. The peaks in XRD pattern are in good agreement with that of face-centered-cubic form of metallic silver. TGA/DTA results confirmed the weight loss and the exothermic reaction due to desorption of chemisorbed water. The temperature dependence of resistivity of silver thin film, determined in the temperature range of 100-300 K, exhibit semiconducting behavior of the sample. The sample shows the activated variable range hopping in the localized states near the Fermi level.

Majeed Khan, Mohd Abdul; Kumar, Sushil; Ahamed, Maqusood; Alrokayan, Salman A.; Alsalhi, Mohammad Saleh

2011-06-01

207

One-step synthesis of silver nanoparticle-filled Nylon 6 nanofibers and their antibacterial properties  

Technology Transfer Automated Retrieval System (TEKTRAN)

A novel and facile one-step approach to in situ synthesize silver nanoparticle-filled nylon 6 nanofibers by electrospinning is reported. The method does not need post-treatments and can be carried out at ambient conditions without using additional chemicals. It employs the electrospinning solvent as...

208

Silver nanoparticle-DNA bionanoconjugates bearing a discrete number of DNA ligands.  

PubMed

Silver nanoparticles (AgNPs), which are stable in strongly ionic solutions and appear as a single sharp band during gel electrophoresis, are synthesized by a facile one-pot process, allowing for the first time realization of AgNP-DNA bio-nano-conjugates bearing a discrete number of DNA ligands. PMID:22588332

Zheng, Yuanqin; Li, Yulin; Deng, Zhaoxiang

2012-06-21

209

Synthesis of silver nanoparticles in textile finish aqueous system and their antimicrobial properties on cotton fibers  

Technology Transfer Automated Retrieval System (TEKTRAN)

Silver nanoparticles (NPs) were synthesized by a simple and environmentally benign procedure using poly (ethylene glycol) (PEG) as reducing agent and stabilizer in the textile finish aqueous system, and their antimicrobial properties on greige (mechanically cleaned) and bleached cotton fibers were i...

210

Antibacterial wound dressing from chitosan/polyethylene oxide nanofibers mats embedded with silver nanoparticles.  

PubMed

Novel antibacterial nanomaterials have been developed for biomedical applications. The present study involves the preparation and properties of antibacterial nanofibers from chitosan/polyethylene oxide electrospun nanofibers incorporated with silver nanoparticles. Silver nanoparticles were efficiently synthesized in situ after ultra violet (UV) with AgNO3 as precursor and chitosan/polyethylene oxide as reducing agent and protecting agent, respectively. Then the resultant solutions were electrospun into nanofibers. The formation of silver nanoparticles was confirmed with ultraviolet visible (UV-vis) and transmission electron microscopy (TEM), and the electrospun nanofibers were characterized by scanning electron microscopy and energy dispersive X-ray. The resultant fibers exhibited uniform morphology with silver nanoparticles distributed throughout the fiber. Also, the fibers showed certain tensile strength and excellent antibacterial activity against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Sustained release of silver nanoparticles from fibers could last for over 72?h. The silver-containing chitosan/polyethylene oxide nanofibers showed excellent cytocompatibility. PMID:25281643

Wang, Xiaoli; Cheng, Feng; Gao, Jing; Wang, Lu

2015-03-01

211

Biotemplates in the green synthesis of silver nanoparticles.  

PubMed

This article recapitulates the scientific advancement towards the greener synthesis of silver nanoparticles. Applications of noble metals have increased throughout human civilization, and the uses for nano-sized particles are even more remarkable. "Green" nanoparticle synthesis has been achieved using environmentally acceptable solvent systems and eco-friendly reducing and capping agents. Numerous microorganisms and plant extracts have been applied to synthesize inorganic nanostructures either intracellularly or extracellularly. The use of nanoparticles derived from noble metals has spread to many areas including jewelery, medical fields, electronics, water treatment and sport utilities, thus improving the longevity and comfort in human life. The application of nanoparticles as delivery vehicles for bactericidal agents represents a new paradigm in the design of antibacterial therapeutics. Orientation, size and physical properties of nanoparticles influences the performance and reproducibility of a potential device, thus making the synthesis and assembly of shape- and size-controlled nanocrystals an essential component for any practical application. This need has motivated researchers to explore different synthesis protocols. PMID:20669257

Vijayaraghavan, Krishnan; Nalini, S P Kamala

2010-10-01

212

Active Silver Nanoparticles for Wound Healing  

PubMed Central

In this preliminary study, the silver nanoparticle (Ag NP)-based dressing, Acticoat™ Flex 3, has been applied to a 3D fibroblast cell culture in vitro and to a real partial thickness burn patient. The in vitro results show that Ag NPs greatly reduce mitochondrial activity, while cellular staining techniques show that nuclear integrity is maintained, with no signs of cell death. For the first time, transmission electron microscopy (TEM) and inductively coupled plasma mass spectrometry (ICP-MS) analyses were carried out on skin biopsies taken from a single patient during treatment. The results show that Ag NPs are released as aggregates and are localized in the cytoplasm of fibroblasts. No signs of cell death were observed, and the nanoparticles had different distributions within the cells of the upper and lower dermis. Depth profiles of the Ag concentrations were determined along the skin biopsies. In the healed sample, most of the silver remained in the surface layers, whereas in the unhealed sample, the silver penetrated more deeply. The Ag concentrations in the cell cultures were also determined. Clinical observations and experimental data collected here are consistent with previously published articles and support the safety of Ag NP-based dressing in wound treatment. PMID:23455461

Rigo, Chiara; Ferroni, Letizia; Tocco, Ilaria; Roman, Marco; Munivrana, Ivan; Gardin, Chiara; Cairns, Warren R. L.; Vindigni, Vincenzo; Azzena, Bruno; Barbante, Carlo; Zavan, Barbara

2013-01-01

213

Preparation of solid silver nanoparticles for inkjet printed flexible electronics with high conductivity  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (NPs) which could be kept in solid form and were easily stored without degeneration or oxidation at room temperature for a long period of time were synthesized by a simple and environmentally friendly wet chemistry method in an aqueous phase. Highly stable dispersions of aqueous silver NP inks, sintered at room temperature, for printing highly conductive tracks (~8.0 ?? cm) were prepared simply by dispersing the synthesized silver NP powder in water. These inks are stable, fairly homogeneous and suitable for a wide range of patterning techniques. The inks were successfully printed on paper and polyethylene terephthalate (PET) substrates using a common color printer. Upon annealing at 180 °C, the resistivity of the printed silver patterns decreased to 3.7 ?? cm, which is close to twice that of bulk silver. Various factors affecting the resistivity of the printed silver patterns, such as annealing temperature and the number of printing cycles, were investigated. The resulting high conductivity of the printed silver patterns reached over 20% of the bulk silver value under ambient conditions, which enabled the fabrication of flexible electronic devices, as demonstrated by the inkjet printing of conductive circuits of LED devices.Silver nanoparticles (NPs) which could be kept in solid form and were easily stored without degeneration or oxidation at room temperature for a long period of time were synthesized by a simple and environmentally friendly wet chemistry method in an aqueous phase. Highly stable dispersions of aqueous silver NP inks, sintered at room temperature, for printing highly conductive tracks (~8.0 ?? cm) were prepared simply by dispersing the synthesized silver NP powder in water. These inks are stable, fairly homogeneous and suitable for a wide range of patterning techniques. The inks were successfully printed on paper and polyethylene terephthalate (PET) substrates using a common color printer. Upon annealing at 180 °C, the resistivity of the printed silver patterns decreased to 3.7 ?? cm, which is close to twice that of bulk silver. Various factors affecting the resistivity of the printed silver patterns, such as annealing temperature and the number of printing cycles, were investigated. The resulting high conductivity of the printed silver patterns reached over 20% of the bulk silver value under ambient conditions, which enabled the fabrication of flexible electronic devices, as demonstrated by the inkjet printing of conductive circuits of LED devices. Electronic supplementary information (ESI) available: Additional figures. See DOI: 10.1039/c3nr05479a

Shen, Wenfeng; Zhang, Xianpeng; Huang, Qijin; Xu, Qingsong; Song, Weijie

2014-01-01

214

Caging antimicrobial silver nanoparticles inside cotton  

Technology Transfer Automated Retrieval System (TEKTRAN)

In this study, a stable, non-leaching Ag-cotton nanocomposite fiber has been characterized. Siver nanoparticles (Ag NPs) were previously synthesized in the alkali-swollen substructure of cotton fiber; the nano-sized micofibrillar channels allowed diffusion-controlled conditions to produce mono-dispe...

215

Chitin membranes containing silver nanoparticles for wound dressing application.  

PubMed

Silver nanoparticles are gaining importance as an antimicrobial agent in wound dressings. Chitin is a biopolymer envisioned to promote rapid dermal regeneration and accelerate wound healing. This study was focused on the evaluation of chitin membranes containing silver nanoparticles for use as an antimicrobial wound dressing. Silver nanoparticles were synthesised by gamma irradiation at doses of 50 kGy in the presence of sodium alginate as stabiliser. The UV-Vis absorption spectra of nanoparticles exhibited an absorption band at 415-420 nm, which is the typical plasmon resonance band of silver nanoparticles. The peaks in the X-ray diffraction (XRD) pattern are in agreement with the standard values of the face-centred cubic silver. Transmission electron microscopy (TEM) images indicate silver nanoparticles with spherical morphology and small particle size in the range of 3-13 nm. In vitro antimicrobial tests were performed using Pseudomonas aeruginosa and Staphylococcus aureus to determine the antimicrobial efficiency of the chitin membranes containing 30, 50, 70 and 100 ppm nanosilver. No viable counts for P. aeruginosa were detected with 70 ppm silver nanoparticles dressing after 1-hour exposure. A 2-log reduction in viable cell count was observed for S. aureus after 1 hour and a 4-log reduction after 6 hours with 100 ppm nanosilver chitin membranes. This study demonstrates the antimicrobial capability of chitin membranes containing silver nanoparticles. The chitin membranes with 100 ppm nanosilver showed promising antimicrobial activity against common wound pathogens. PMID:22958740

Singh, Rita; Singh, Durgeshwer

2014-06-01

216

Transformation of Silver Nanoparticles in Fresh, Aged, and Incinerated Biosolids  

EPA Science Inventory

Abstract The purpose of this research was to assess the chemical transformation of silver nanoparticles (AgNPs) in aged, fresh, and incinerated biosolids in order to provide information for AgNP life cycle analyses. Silver nanoparticles were introduced to the influent of a pilot...

217

Tuning of optical properties of PMMA by incorporating silver nanoparticles  

NASA Astrophysics Data System (ADS)

Nanocomposite films of Poly (methylmethacrylate) filled with different concentration of silver nanoparticles were prepared by ex-situ method. Firstly, silver nanoparticles were obtained by reducing the aqueous solution of silver nitrate with sodium borohydride then Ag/PMMA films were prepared by mixing colloidal solution of silver nanoparticles with solution of polymer. From absorption and specular reflection spectra, the optical band gap and refractive index (n) have been calculated. The decrease in optical bandgap and increase in refractive index has been indicative of the modifications in optical band structure of the PMMA matrix.

Alisha, Rozra, Jyoti; Saini, Isha; Sharma, Annu; Sharma, Pawan

2012-06-01

218

Synthesis and characterization of cysteine functionalized silver nanoparticles for biomolecule immobilization.  

PubMed

A facile method for the aqueous phase synthesis of cysteine-functionalized silver nanoparticles by potato extract has been reported in the present work. These functionalized nanoparticles were then used for the covalent immobilization of a biomolecule, alkaline phosphatase, on its surface through carbodiimide coupling. Different reaction parameters such as cysteine concentration, reducing agent concentration, temperature, pH and reaction time were varied during the nanoparticles' formation, and their effects on plasmon resonance were studied using Ultraviolet-visible spectroscopy. Fourier transform infrared spectroscopy was used to confirm the surface modification of silver nanoparticles by cysteine and the particle size analysis was done using particle size analyzer, which showed the average nanoparticles' size of 61 nm for bare silver nanoparticles and 201 nm for the enzyme-immobilized nanoparticles. The synthesized nanoparticles were found to be highly efficient for the covalent immobilization of alkaline phosphatase on its surface and retained 67% of its initial enzyme activity (9.44 U/mg), with 75% binding efficiency. The shelf life of the enzyme-nanoparticle bioconjugates was found to be 60 days, with a 12% loss in the initial enzyme activity. With a simple synthesis strategy, high immobilization efficiency and enhanced stability, these enzyme-coated nanoparticles have the potential for further integration into the biosensor technology. PMID:24760173

Upadhyay, Lata Sheo Bachan; Verma, Nishant

2014-11-01

219

Invertebrate water extracts as biocompatible reducing agents for the green synthesis of gold and silver nanoparticles.  

PubMed

We report the use of water extracts of two invertebrates, snail body and earthworm, as biocompatible reducing agents for the green synthesis of gold and silver nanoparticles. The reaction conditions were optimized by varying the extract concentration, gold ion or silver ion concentration, reaction time, and reaction temperature. The gold and silver nanoparticles exhibited their characteristic surface plasmon resonance bands. Mostly spherical and amorphous shapes of the nanoparticles were synthesized. The average diameters of the gold and silver nanoparticles were 4.56 +/- 1.81 nm and 11.12 +/- 5.25 nm, respectively, when the extract of snail body was used as the reducing agent. The earthworm extracts produced gold and silver nanoparticles with average diameters of 6.70 +/- 2.69 nm and 12.19 +/- 4.28 nm, respectively. This report suggests that the invertebrate natural products have potential as biocompatible reducing agents for the green synthesis of metallic nanoparticles. This utility would open up novel applications of invertebrate natural products as nanocomposites and in nanomedicine. PMID:24079190

Han, Lina; Kim, Yeong Shik; Cho, Seonho; Park, Youmie

2013-08-01

220

Intracellular synthesis of silver nanoparticle by actinobacteria and its antimicrobial activity.  

PubMed

Intracellular synthesis of silver nanoparticles (AgNPs) using Rhodococcus spp. is demonstrated. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier trans-form infrared spectroscopy, and transmission electron microscopy. Transmission electron microscopy study of microorganisms' revealed synthesis of nanoparticle was occurring inside the cell, in the cytoplasm. AgNPs ranged from 5 to 50nm. Formed nanoparticles were stable in the colloidal solution due to presence of proteins on the surface. AgNPs showed excellent bactericidal and bacteriostatic activity against pathogenic microorganisms. PMID:25456659

Otari, S V; Patil, R M; Ghosh, S J; Thorat, N D; Pawar, S H

2015-02-01

221

Intracellular synthesis of silver nanoparticle by actinobacteria and its antimicrobial activity  

NASA Astrophysics Data System (ADS)

Intracellular synthesis of silver nanoparticles (AgNPs) using Rhodococcus spp. is demonstrated. The synthesized nanoparticles were characterized by UV-Vis spectroscopy, X-ray diffraction, energy dispersive spectroscopy, Fourier trans-form infrared spectroscopy, and transmission electron microscopy. Transmission electron microscopy study of microorganisms' revealed synthesis of nanoparticle was occurring inside the cell, in the cytoplasm. AgNPs ranged from 5 to 50 nm. Formed nanoparticles were stable in the colloidal solution due to presence of proteins on the surface. AgNPs showed excellent bactericidal and bacteriostatic activity against pathogenic microorganisms.

Otari, S. V.; Patil, R. M.; Ghosh, S. J.; Thorat, N. D.; Pawar, S. H.

2015-02-01

222

Silver and gold nanoparticles for sensor and antibacterial applications.  

PubMed

Green biogenic method for the synthesis of gold and silver nanoparticles using Solanum lycopersicums extract as reducing agent was studied. The biomolecules present in the extract was responsible for reduction of Au(3+) and Ag(+) ions from HAuCl4 and AgNO3 respectively. The prepared nanoparticles were characterized by UV-visible spectroscopy (UV-vis), Fourier transform infrared spectroscopy (FTIR), Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) technique to identify the size, shape of nanoparticles and biomolecules act as reducing agents. UV-visible spectra show the surface plasmon resonance peak at 546 nm and 445 nm corresponding to gold and silver nanoparticles respectively. Crystalline nature of the nanoparticles was evident from TEM images and XRD analysis. TEM images showed average size of 14 nm and 12 nm for prepared gold and silver nanoparticles respectively. FTIR analysis provides the presence of biomolecules responsible for the reduction and stability of the prepared silver and gold nanoparticles. XRD analysis of the silver and gold nanoparticles confirmed the formation of metallic silver and gold. The prepared gold and silver nanoparticles show good sensing and antimicrobial activity. PMID:24657466

Bindhu, M R; Umadevi, M

2014-07-15

223

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity  

NASA Astrophysics Data System (ADS)

Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics.

Ashraf, Sumaira; Akhtar, Nasrin; Ghauri, Muhammad Afzal; Rajoka, Muhammad Ibrahim; Khalid, Zafar M.; Hussain, Irshad

2012-05-01

224

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity  

PubMed Central

Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics. PMID:22625664

2012-01-01

225

Polyhexamethylene biguanide functionalized cationic silver nanoparticles for enhanced antimicrobial activity.  

PubMed

Polyhexamethylene biguanide (PHMB), a broad spectrum disinfectant against many pathogens, was used as a stabilizing ligand for the synthesis of fairly uniform silver nanoparticles. The particles formed were characterized using UV-visible spectroscopy, FTIR, dynamic light scattering, electrophoretic mobility, and TEM to measure their morphology and surface chemistry. PHMB-functionalized silver nanoparticles were then evaluated for their antimicrobial activity against a gram-negative bacterial strain, Escherichia coli. These silver nanoparticles were found to have about 100 times higher bacteriostatic and bactericidal activities, compared to the previous reports, due to the combined antibacterial effect of silver nanoparticles and PHMB. In addition to other applications, PHMB-functionalized silver nanoparticles would be extremely useful in textile industry due to the strong interaction of PHMB with cellulose fabrics. PMID:22625664

Ashraf, Sumaira; Akhtar, Nasrin; Ghauri, Muhammad Afzal; Rajoka, Muhammad Ibrahim; Khalid, Zafar M; Hussain, Irshad

2012-01-01

226

Comparison of bioconcentration of ionic silver and silver nanoparticles in zebrafish eleutheroembryos.  

PubMed

The production of silver nanoparticles has reached nowadays high levels. Bioconcentration studies, information on persistence and toxicity are fundamental to assess their global risk and thus necessary to establish legislations regarding their use. Previous studies on silver nanoparticle toxicity have determined a clear correlation between their chemical stability and toxicity. In this work, experimental conditions able to assure silver nanoparticles stability have been optimized. Then, zebrafish (Danio rerio) eleutheroembryos were exposed to ionic silver and to Ag NPs for comparison purposes. A protocol alternative to the OECD 305 technical guideline was used. To determine silver concentration in both the eleutheroembryos and the exposure media, an analytical method consisting in ultrasound assisted extraction, followed by inductively coupled plasma mass spectrometry and graphite furnace atomic absorption spectrometry, was developed. Then, bioconcentration factors were calculated. The results revealed that ionic silver was more accumulative for zebrafish eleutheroembryos than nanoparticles at the levels tested. PMID:24858804

López-Serrano, A; Muñoz-Olivas, R; Sanz-Landaluze, J; Olasagasti, M; Rainieri, S; Cámara, C

2014-08-01

227

Green synthesis of water-soluble nontoxic polymeric nanocomposites containing silver nanoparticles  

PubMed Central

New water-soluble nontoxic nanocomposites of nanosized silver particles in a polymer matrix were synthesized by a green chemistry method. Nontoxic poly(1-vinyl-1,2,4-triazole) was used as a stabilizing precursor agent in aqueous medium. Glucose and dimethyl sulfoxide were used as the silver ion-reducing agents to yield silver nanoparticles 2–26 nm and 2–8 nm in size, respectively. The nanocomposites were characterized by transmission electron microscopy, ultraviolet-visible and Fourier transform infrared spectroscopy, X-ray diffraction, atomic absorption, and thermogravimetric data analysis. The nanocomposites showed strong antimicrobial activity against Gram-negative and Gram-positive bacteria. PMID:24790430

Prozorova, Galina F; Pozdnyakov, Alexsandr S; Kuznetsova, Nadezhda P; Korzhova, Svetlana A; Emel’yanov, Artem I; Ermakova, Tamara G; Fadeeva, Tat’yana V; Sosedova, Larisa M

2014-01-01

228

Investigation of antibacterial properties silver nanoparticles prepared via green method  

PubMed Central

Background This study aims to investigate the influence of different stirring times on antibacterial activity of silver nanoparticles in polyethylene glycol (PEG) suspension. The silver nanoparticles (Ag-NPs) were prepared by green synthesis method using green agents, polyethylene glycol (PEG) under moderate temperature at different stirring times. Silver nitrate (AgNO3) was taken as the metal precursor while PEG was used as the solid support and polymeric stabilizer. The antibacterial activity of different sizes of nanosilver was investigated against Gram–positive [Staphylococcus aureus] and Gram–negative bacteria [Salmonella typhimurium SL1344] by the disk diffusion method using Müeller–Hinton Agar. Results Formation of Ag-NPs was determined by UV–vis spectroscopy where surface plasmon absorption maxima can be observed at 412–437 nm from the UV–vis spectrum. The synthesized nanoparticles were also characterized by X-ray diffraction (XRD). The peaks in the XRD pattern confirmed that the Ag-NPs possessed a face-centered cubic and peaks of contaminated crystalline phases were unable to be located. Transmission electron microscopy (TEM) revealed that Ag-NPs synthesized were in spherical shape. The optimum stirring time to synthesize smallest particle size was 6 hours with mean diameter of 11.23 nm. Zeta potential results indicate that the stability of the Ag-NPs is increases at the 6 h stirring time of reaction. The Fourier transform infrared (FT-IR) spectrum suggested the complexation present between PEG and Ag-NPs. The Ag-NPs in PEG were effective against all bacteria tested. Higher antibacterial activity was observed for Ag-NPs with smaller size. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field. Conclusions Ag-NPs were successfully synthesized in PEG suspension under moderate temperature at different stirring times. The study clearly showed that the Ag-NPs with different stirring times exhibit inhibition towards the tested gram-positive and gram-negative bacteria. PMID:22839208

2012-01-01

229

Synthesis of silver nanoparticles using Nelumbo nucifera leaf extract and its larvicidal activity against malaria and filariasis vectors  

Microsoft Academic Search

The aim of this study was to investigate the larvicidal potential of the hexane, chloroform, ethyl acetate, acetone, methanol,\\u000a and aqueous leaf extracts of Nelumbo nucifera Gaertn. (Nymphaeaceae) and synthesized silver nanoparticles using aqueous leaf extract against fourth instar larvae of Anopheles subpictus Grassi and Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was

Thirunavukkarasu Santhoshkumar; Abdul Abdul Rahuman; Govindasamy Rajakumar; Sampath Marimuthu; Asokan Bagavan; Chidambaram Jayaseelan; Abdul Abduz Zahir; Gandhi Elango; Chinnaperumal Kamaraj

2011-01-01

230

The targeted antibacterial and antifungal properties of magnetic nanocomposite of iron oxide and silver nanoparticles.  

PubMed

Two types of magnetic binary nanocomposites, Ag@Fe(3)O(4) and ?-Fe(2)O(3)@Ag, were synthesized and characterized and their antibacterial activities were tested. As a magnetic component, Fe(3)O(4) (magnetite) nanoparticles with an average size of about 70 nm and monodisperse ?-Fe(2)O(3) (maghemite) nanoparticles with an average size of 5 nm were used. Nanocomposites were prepared via in situ chemical reduction of silver ions by maltose in the presence of particular magnetic phase and molecules of polyacrylate serving as a spacer among iron oxide and silver nanoparticles. In the case of the Ag@Fe(3)O(4) nanocomposite, silver nanoparticles, caught at the surfaces of Fe(3)O(4) nanocrystals, were around 5 nm in a size. On the contrary, in the case of the ?-Fe(2)O(3)@Ag nanocomposite, ultrafine ?-Fe(2)O(3) nanoparticles surrounded silver nanoparticles ranging in a size between 20 and 40 nm. In addition, the molecules of polyacrylate in this nanocomposite type suppress considerably interparticle magnetic interactions as proved by magnetization measurements. Both synthesized nanocomposites exhibited very significant antibacterial and antifungal activities against ten tested bacterial strains (minimum inhibition concentrations (MIC) from 15.6 mg/L to 125 mg/L) and four candida species (MIC from 1.9 mg/L to 31.3 mg/L). Moreover, acute nanocomposite cytotoxicity against mice embryonal fibroblasts was observed at concentrations of higher than 430 mg/L (Ag@Fe(3)O(4)) and 292 mg/L (?-Fe(2)O(3)@Ag). With respect to the non-cytotoxic nature of the polyacrylate linker, both kinds of silver nanocomposites are well applicable for a targeted magnetic delivery of silver nanoparticles in medicinal and disinfection applications. PMID:21507482

Prucek, Robert; Tu?ek, Ji?í; Kilianová, Martina; Paná?ek, Aleš; Kvítek, Libor; Filip, Jan; Kolá?, Milan; Tománková, Kate?ina; Zbo?il, Radek

2011-07-01

231

Remobilisation of silver and silver sulphide nanoparticles in soils.  

PubMed

Manufactured nanoparticles (NPs) present in consumer products could enter soils through re-use of biosolids. Among these NPs are those based on silver (Ag), which are found sulphidised (e.g. silver sulphide, Ag2S) in biosolids. Herein, our aim was to examine the release of retained Ag(0) and Ag2S NPs in soils and biosolids as facilitated by environmentally and agriculturally relevant ligands. Under natural soil conditions, exemplified by potassium nitrate and humic acid experiments, release of Ag retained in soil was limited. The highest total Ag release was facilitated by ligands that simulated root exudates (citrate) or fertilisers (thiosulphate). Released Ag was predominantly present in the colloidal phase (>3 kDa-< 0.45 ?m); intact NPs only identified in Ag2S-NP extracts. For biosolids containing nanoparticulate-Ag-S, release was also enhanced by thiosulphate, though mostly as colloidal-Ag - not intact NPs. These results suggest that exposure to NPs as a result of its release from soils or biosolids will be low. PMID:25014017

Navarro, Divina A; Kirby, Jason K; McLaughlin, Mike J; Waddington, Lynne; Kookana, Rai S

2014-10-01

232

Biological coating of paper using silver nanoparticles.  

PubMed

The capacity of Ag nanoparticles to destroy various micro-organisms makes it one of the most powerful antimicrobial agents, an attractive feature against antibiotic resistant bacteria. Here, a simple method to develop coating of colloidal silver on paper using a biological method is presented. The coated paper was studied by scanning electron microscopy, X-ray diffraction technique and atomic absorption spectroscopy. The antibacterial activity of the coated paper against Escherichia coli and Staphylococcus aureus was measured by agar diffusion method. This study shows the potential use of the coated paper as a food antimicrobial packing material for longer shelf life. PMID:25429506

Ghorbani, Hamid Reza

2014-12-01

233

Green Synthesis of Silver Nanoparticles Using Pinus eldarica Bark Extract  

PubMed Central

Recently, development of reliable experimental protocols for synthesis of metal nanoparticles with desired morphologies and sizes has become a major focus of researchers. Green synthesis of metal nanoparticles using organisms has emerged as a nontoxic and ecofriendly method for synthesis of metal nanoparticles. The objectives of this study were production of silver nanoparticles using Pinus eldarica bark extract and optimization of the biosynthesis process. The effects of quantity of extract, substrate concentration, temperature, and pH on the formation of silver nanoparticles are studied. TEM images showed that biosynthesized silver nanoparticles (approximately in the range of 10–40?nm) were predominantly spherical in shape. The preparation of nano-structured silver particles using P. eldarica bark extract provides an environmentally friendly option, as compared to currently available chemical and/or physical methods. PMID:24083233

Iravani, Siavash; Zolfaghari, Behzad

2013-01-01

234

Enhancement of antidandruff activity of shampoo by biosynthesized silver nanoparticles from Solanum trilobatum plant leaf  

NASA Astrophysics Data System (ADS)

The present investigation describes simple and effective method for synthesis of silver nanoparticles via green route. Solanum trilobatum Linn extract were prepared by both conventional and homogenization method. We optimized the production of silver nanoparticles under sunlight, microwave and room temperature. The best results were obtained with sunlight irradiation, exhibiting 15-20 nm silver nanoparticles having cubic and hexagonal shape. Biosynthesized nanoparticles were highly toxic to various bacterial strains tested. In this study we report antibacterial activity against various Gram negative ( Klebsiella pneumoniae, Vibrio cholerae and Salmonella typhi) and Gram positive ( Staphylococcus aureus, Bacillus cereus and Micrococcus luteus) bacterial strains. Screening was also performed for any antifungal properties of the nanoparticles against human pathogenic fungal strains ( Candida albicans and Candida parapsilosis). We also demonstrated that these nanoparticles when mixed with shampoo enhance the anti-dandruff effect against dandruff causing fungal pathogens ( Pityrosporum ovale and Pityrosporum folliculitis). The present study showed a simple, rapid and economical route to synthesize silver nanoparticles and their applications hence has a great potential in biomedical field.

Pant, Gaurav; Nayak, Nitesh; Gyana Prasuna, R.

2013-10-01

235

Toxicity of Silver Nanoparticles at the Air-Liquid Interface  

PubMed Central

Silver nanoparticles are one of the most prevalent nanomaterials in consumer products. Some of these products are likely to be aerosolized, making silver nanoparticles a high priority for inhalation toxicity assessment. To study the inhalation toxicity of silver nanoparticles, we have exposed cultured lung cells to them at the air-liquid interface. Cells were exposed to suspensions of silver or nickel oxide (positive control) nanoparticles at concentrations of 2.6, 6.6, and 13.2??g cm?2 (volume concentrations of 10, 25, and 50??g?ml?1) and to 0.7??g?cm?2 silver or 2.1??g?cm?2 nickel oxide aerosol at the air-liquid interface. Unlike a number of in vitro studies employing suspensions of silver nanoparticles, which have shown strong toxic effects, both suspensions and aerosolized nanoparticles caused negligible cytotoxicity and only a mild inflammatory response, in agreement with animal exposures. Additionally, we have developed a novel method using a differential mobility analyzer to select aerosolized nanoparticles of a single diameter to assess the size-dependent toxicity of silver nanoparticles. PMID:23484109

Holder, Amara L.; Marr, Linsey C.

2013-01-01

236

Characterization and antimicrobial activity of silver nanoparticles prepared by a thermal decomposition technique  

NASA Astrophysics Data System (ADS)

Recently, there has been an increasing need of efficient synthetic protocols using eco-friendly conditions including low costs and green chemicals for production of metal nanoparticles. In this work, silver nanoparticles (silver NPs) with average particle size about 10 nm were synthesized by using a thermal decomposition technique. Unlike the colloidal chemistry method, the thermal decomposition method developed has advantages such as the high crystallinity, single-reaction synthesis, and easy dispersion ability of the synthesized NPs in organic solvents. In a modified synthesis process, we used sodium oleate as a capping agent to modify the surface of silver NPs because the oleate has a C18 tail with a double bond in the middle, therefore, forming a kink which is to be effective for aggregative stability. Importantly, the as-synthesized silver NPs have demonstrated strong antimicrobial effects against various bacteria and fungi strains. Electron microscopic studies reveal physical insights into the interaction and bactericidal mechanism between the prepared silver NPs and tested bacteria in question. The observed excellent antibacterial and antifungal activity of the silver NPs make them ideal for disinfection and biomedicine applications.

Tam, Le Thi; Phan, Vu Ngoc; Lan, Hoang; Thuy, Nguyen Thanh; Hien, Tran Minh; Huy, Tran Quang; Quy, Nguyen Van; Chinh, Huynh Dang; Tung, Le Minh; Tuan, Pham Anh; Lam, Vu Dinh; Le, Anh-Tuan

2013-11-01

237

Shape-Controlled Synthesis of Gold and Silver Nanoparticles  

Microsoft Academic Search

Monodisperse samples of silver nanocubes were synthesized in large quantities by reducing silver nitrate with ethylene glycol in the presence of poly(vinyl pyrrolidone) (PVP). These cubes were single crystals and were characterized by a slightly truncated shape bounded by {100}, {110}, and {111} facets. The presence of PVP and its molar ratio (in terms of repeating unit) relative to silver

Yugang Sun; Younan Xia

2002-01-01

238

Biological Mechanism of Silver Nanoparticle Toxicity  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (AgNPs), like almost all nanoparticles, are potentially toxic beyond a certain concentration because the survival of the organism is compromised due to scores of pathophysiological abnormalities above that concentration. However, the mechanism of AgNP toxicity remains undetermined. Instead of applying a toxic dose, these investigations were attempted to monitor the effects of AgNPs at a non-lethal concentration on wild type Drosophila melanogaster by exposing them to nanoparticles throughout their development. All adult flies raised in AgNP doped food indicated that of not more than 50 mg/L had no negative influence on median survival; however, these flies appeared uniformly lighter in body color due to the loss of melanin pigments in their cuticle. Additionally, fertility and vertical movement ability were compromised after AgNP feeding. The determination of the amount of free ionic silver (Ag+) indicated that the observed biological effects had resulted from the AgNPs and not from Ag+. Biochemical analysis suggests that the activity of copper dependent enzymes, namely tyrosinase and Cu-Zn superoxide dismutase, were decreased significantly following the consumption of AgNPs, despite the constant level of copper present in the tissue. Furthermore, copper supplementation restored the loss of AgNP induced demelanization, and the reduction of functional Ctr1 in Ctr1 heterozygous mutants caused the flies to be resistant to demelanization. Consequently, these studies proposed a mechanism whereby consumption of excess AgNPs in association with membrane bound copper transporter proteins cause sequestration of copper, thus creating a condition that resembles copper starvation. This model also explained the cuticular demelanization effect resulting from AgNP since tyrosinase activity is essential for melanin biosynthesis. Finally, these investigations demonstrated that Drosophila, an established genetic model system, can be well utilized for further characterizing the biological effects of nanoparticles.

Armstrong, Najealicka Nicole

239

A Facile Route for Synthesis of Octyl Amine Capped Silver Nanoparticle  

NASA Astrophysics Data System (ADS)

This paper presents a simple and convenient procedure for the preparation of octyl amine capped silver nanoparticles. AgNO3 has been reduced by octyl amine with benzene or toluene as solvent at 100°C to produce silver nanoparticles. Octyl amine plays its role both as reducing and capping agent and thus provides the advantage of avoiding the use of extra stabilizing agent. Time dependent formation mechanism of silver nanoparticle has been investigated. Thermo gravimetric analysis (TGA) shows weight change due to loss of capping agent. The reaction can easily be monitored from variation of color with time. The method is easy and reproducible. Very low concentration (1 mM) of metal ion is used. The particles synthesized were characterized by UV-Visible, FTIR, TGA, TEM and X-ray diffraction studies.

Agasti, Nityananda; Kaushik, N. K.

2014-11-01

240

Spectroscopy study of silver nanoparticles fabrication using synthetic humic substances and their antimicrobial activity.  

PubMed

In this present study, silver nanoparticles were synthesized using synthetic humic substances (HSs) as reducing and stabilizing agents. Preference of synthetic HSs over natural humic matter is determined by a standardization problem resolution of the product due to the strict control of conditions of the synthetic HSs formation. It allows to receive the silver nanoparticles with the standardized biologically-active protective shell that is very important for their use, mainly in medicine. The concentration of sodium hydroxide, synthetic HSs, silver nitrate and temperature employed in the synthesis process are optimized to attain better yield, controlled size and stability by means of UV-visible technique. In the optimal reaction conditions the concentrated silver colloids (55 mM) with 99.99% yield are obtained which were stable for more than 1 year under ambient conditions. The received silver nanoparticles are characterized by UV-visible spectroscopy, X-ray diffraction (XRD), FT-IR spectroscopy and transmission electron microscopy (TEM). The antimicrobial activity of silver nanoparticles against fungal and bacterial strains is also shown. PMID:23466321

Litvin, Valentina A; Minaev, Boris F

2013-05-01

241

A Novel Photosynthesis of Carboxymethyl Starch-Stabilized Silver Nanoparticles  

PubMed Central

The water soluble photoinitiator (PI) 4-(trimethyl ammonium methyl) benzophenone chloride is used for the first time in the synthesis of silver nanoparticles (AgNPs). A new green synthesis method involves using PI/UV system, carboxymethyl starch (CMS), silver nitrate, and water. A mechanism of the reduction of silver ions to AgNPs by PI/UV system as well as by the newly born aldehydic groups was proposed. The synthesis process was assessed by UV-vis spectra and TEM of AgNPs colloidal solution. The highest absorbance was obtained using CMS, PI and AgNO3 concentrations of 10?g/L, 1?g/L, and 1?g/L, respectively; 40°C; 60?min; pH 7; and a material?:?liquor ratio 1?:?20. AgNPs so-obtained were stable in aqueous solution over a period of three weeks at room temperature (~25°C) and have round shape morphology. The sizes of synthesized AgNPs were in the range of 1–21?nm and the highest counts % of these particles were for particles of 6–10 and 1–3?nm, respectively. PMID:24672325

El-Sheikh, M. A.

2014-01-01

242

A study on the stability and green synthesis of silver nanoparticles using Ziziphora tenuior (Zt) extract at room temperature  

NASA Astrophysics Data System (ADS)

Biomolecules present in plant extracts can be used to reduce metal ions to nanoparticles in a single-step green synthesis process. This biogenic reduction of metal ion to base metal is quite rapid, readily conducted at room temperature and pressure, and easily scaled up. Mediated Synthesis by plant extracts is environmentally benign. The involved reducing agents include the various water soluble plant metabolites (e.g. alkaloids, phenolic compounds, terpenoids) and co-enzymes. Silver (Ag) nanoparticles have the particular focus of plant-based syntheses. Extracts of a diverse range of Ziziphora tenuior (Zt) have been successfully used in making nanoparticles. The aim of this study was to investigate the antioxidant properties of this plant and its ability to synthesize silver nanoparticles. Z.tenuior leaves were used to prepare the aqueous extract for this study. Silver nanoparticles were characterized with different techniques such as UV-vis spectroscopy, Fourier transform infrared (FT-IR) spectroscopy, X-ray diffraction (XRD), Scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Transmission electron microscopy experiments showed that these nanoparticles are spherical and uniformly distributed and its size is from 8 to 40 nm. FT-IR spectroscopy revealed that silver nanoparticles were functionalized with biomolecules that have primary amine group (sbnd NH2), carbonyl group, sbnd OH groups and other stabilizing functional groups. X-ray diffraction pattern showed high purity and face centered cubic structure of silver nanoparticles with size of 38 nm. In addition to plant extracts, live plants can be used for the synthesis. Here were view the methods of making nanoparticles using plant extracts. The scanning electron microscopy (SEM) implies the right of forming silver nanoparticles. The results of TEM, SEM, FT-IR, UV-VIS and XRD confirm that the leaves extract of Zt can synthesis silver nanoparticles.

Sadeghi, Babak; Gholamhoseinpoor, F.

2015-01-01

243

Growth mechanisms of silver nanoparticles: a molecular dynamics study  

NASA Astrophysics Data System (ADS)

The shape control of metal nanoparticles allows one to finely tune their properties with great versatility. A self-seeding coreduction method has recently been developed for the synthesis of silver nanodiscs, triangular nanoplates and nanospheres. The addition of surfactants was found to be one of the most important factors in determining the final particle shape. In this paper, molecular dynamics simulations are performed to understand the growth mechanisms of silver nanoparticles for different surfactants (i.e. bis(2-ethylhexyl) sulfosuccinate, 1-dodecanethiol and cetyltrimethyl ammonium). The interaction energies between the surfactants and the silver crystal plane (i.e. (100), (110), (111)) are calculated. The molecular structural property of surfactants at the silver surface is also examined. It is demonstrated that the calculated interaction energies explain well the growth behaviour observed in the silver nanoparticle systems. Molecular dynamics simulation could provide a theoretical guideline for the choice of surfactants and hence the synthesis of various metal nanoparticles with controlled shape.

Zeng, Qinghua; Jiang, Xuchuan; Yu, Aibing; Lu, Gaoqing Max

2007-01-01

244

Synthesis of silver nanoparticles using DL-alanine for ESR dosimetry applications  

NASA Astrophysics Data System (ADS)

The potential use of alanine for the production of nanoparticles is presented here for the first time. Silver nanoparticles were synthesized using a simple green method, namely the thermal treatment of silver nitrate aqueous solutions with DL-alanine. The latter compound was employed both as a reducing and a capping agent. Particles with average size equal to 7.5 nm, face-centered cubic crystalline structure, narrow size distribution, and spherical shape were obtained. Interaction between the silver ions present on the surface of the nanoparticles and the amine group of the DL-alanine molecule seems to be responsible for reduction of the silver ions and for the stability of the colloid. The bio-hybrid nano-composite was used as an ESR dosimeter. The amount of silver nanoparticles in the nanocomposite was not sufficient to cause considerable loss of tissue equivalency. Moreover, the samples containing nanoparticles presented increased sensitivity and reduced energetic dependence as compared with pure DL-alanine, contributing to the construction of small-sized dosimeters.

Guidelli, Eder José; Ramos, Ana Paula; Zaniquelli, Maria Elisabete D.; Nicolucci, Patricia; Baffa, Oswaldo

2012-03-01

245

Significant modifications in the electrical properties of poly(methyl methacrylate) thin films upon dispersion of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Electrical conductivity of thin solid films of PMMA with dispersed silver nanoparticles, synthesized by a novel method, was studied in dark conditions by changing the applied voltage and temperature and also under photoexcitation (by a mercury lamp, 125 W) at room temperature. Anomalous hysteresis in current-temperature characteristics during heating and cooling cycles was observed. The hysteresis-like behaviour was explained on the basis of the movements of molecules associated with different parts of a PMMA matrix and diffusion of silver nanoparticles in the PMMA matrix. Dark current in the PMMA films with dispersed silver nanoparticles has been observed to be higher than the corresponding current in the PMMA films without silver nanoparticles due to the creation of conduction paths by the silver nanoparticles/nanoclusters. The photoresponse in the thin solid films of PMMA with dispersed silver nanoparticles was the reverse of that observed in thin solid films of PMMA without silver nanoparticles. A decrease in photocurrent under illumination of light was observed due to the destruction of conduction paths by the illumination of light.

Basak, Dhrubajyoti; Karan, Santanu; Mallik, Biswanath

2007-03-01

246

Antiglycating potential of gum arabic capped-silver nanoparticles.  

PubMed

Advanced glycation end products are major contributors to the pathology of diabetes, Alzheimer's disease, and atherosclerosis; accordingly, identification of antiglycation compounds is attracting considerable interest. In the present study, the inhibitory effect of gum arabic capped-silver nanoparticles on advanced glycation end products formation was monitored by several biophysical techniques. Silver nanoparticles were characterized by ultraviolet-visible, high-resolution transmission electron microscopy, and energy-dispersive X-ray spectroscopy. Bovine serum albumin and methylglyoxal mixtures incubated with increasing concentrations of silver nanoparticles showed significant reductions in advanced glycation end product formation that were confirmed by ultraviolet-visible, fluorescence spectrometry, and high-performance liquid chromatography techniques. High-performance liquid chromatography showed decreased adduct formation of glycated protein in the presence of silver nanoparticles. The structural changes induced by silver nanoparticles were further confirmed by circular dichroism and Fourier transform infrared spectroscopy. Strong inhibition of advanced glycation end product formation was observed in the presence of elevated silver nanoparticles. The results of this study suggest that silver nanoparticles are a potent antiglycating agent. PMID:25080376

Ashraf, Jalaluddin M; Ansari, Mohammad Azam; Choi, Inho; Khan, Haris M; Alzohairy, Mohammad A

2014-09-01

247

Successively amplified electrochemical immunoassay based on biocatalytic deposition of silver nanoparticles and silver enhancement.  

PubMed

A successively signal-amplified electrochemical immunoassay has been reported on the basis of the biocatalytic deposition of silver nanoparticles with their subsequent enlargement by nanoparticle-promoted catalytic precipitation of silver from the silver-enhancer solution. The immunoassay was carried out based on a heterogeneous sandwich procedure using polystyrene microwells to immobilize antibody. After all the processes comprising the formation of immunocomplex, biocatalytic deposition of silver nanoparticles and following silver enhancement were completed, the silver on polystyrene microwells was dissolved and quantified by anodic stripping voltammetry (ASV). The effect of relevant experimental conditions, including the concentration of ascorbic acid 2-phosphate (AA-p) substrate and Ag(I) ions, the biocatalytic deposition time, and of crucial importance, the silver enhancement time, were investigated and optimized. The anodic stripping peak current was proportional to the concentration of human IgG in a dynamic range of 0.1-10 ng ml(-1) with a detection limit of 0.03 ng ml(-1). Scanning electron microscope (SEM) was applied to characterize the silver nanoparticles before and after silver enhancement on the surface of polystyrene microplates. By coupling the highly catalytic effect of enzyme and nanoparticles to successively amplify the analytical signal, the sensitivity of immunoassay was enhanced so dramatically that this approach would be a promising strategy to achieve a lower detection limit for bioassays. PMID:17720472

Chen, Zhao-Peng; Peng, Zhao-Feng; Luo, Yan; Qu, Bo; Jiang, Jian-Hui; Zhang, Xiao-Bing; Shen, Guo-Li; Yu, Ru-Qin

2007-11-30

248

Synthesis of silver and gold nanoparticles by a novel electrochemical method.  

PubMed

Spherical silver and gold nanoparticles with narrow size distributions were conveniently synthesized in aqueous solution by a novel electrochemical method. The technological keys to the electrochemical synthesis of monodispersed metallic nanoparticles lie in the choice of an ideal stabilizer for the metallic nanoclusters and the use of a rotating platinum cathode. Poly(N-vinylpyrrolidone) (PVP) was chosen as the stabilizer for the silver and gold clusters. PVP not only protects metallic particles from agglomeration, but also promotes metal nucleation, which tends to produce small metal particles. Using a rotating platinum cathode effectively solves the technological difficulty of rapidly transferring the (electrochemically synthesized) metallic nanoparticles from the cathode vicinity to the bulk solution, avoiding the occurrence of flocculates in the vicinity of the cathode, and ensuring the monodispersity of the particles. The particle size and particle size distribution of the silver and gold nanoparticles were improved by adding sodium dodecyl benzene sulfonate (SDBS) to the electrolyte. The electrochemically synthesized nanoparticles were characterized by TEM and UV/Vis spectroscopy. PMID:14999845

Ma, Houyi; Yin, Bingsheng; Wang, Shuyun; Jiao, Yongli; Pan, Wei; Huang, Shaoxin; Chen, Shenhao; Meng, Fanjun

2004-01-23

249

Synthesis of silver nanoparticles in montmorillonite and their antibacterial behavior  

PubMed Central

Silver nanoparticles (Ag NPs) were synthesized by the chemical reducing method in the external and interlamellar space of montmorillonite (MMT) as a solid support at room temperature. AgNO3 and NaBH4 were used as a silver precursor and reducing agent, respectively. The most favorable experimental conditions for synthesizing Ag NPs in the MMT are described in terms of the initial concentration of AgNO3. The interlamellar space limits changed little (d-spacing = 1.24–1.47 nm); therefore, Ag NPs formed on the MMT suspension with d-average = 4.19–8.53 nm diameter. The Ag/MMT nanocomposites (NCs), formed from AgNO3/MMT suspension, were characterizations with different instruments, for example UV-visible, PXRD, TEM, SEM, EDXRF, FT-IR, and ICP-OES analyzer. The antibacterial activity of different sizes of Ag NPs in MMT were investigated against Gram-positive, ie, Staphylococcus aureus and methicillin-resistant S. aureus (MRSA) and Gram-negative bacteria, ie, Escherichia coli, Escherichia coli O157:H7, and Klebsiella pneumoniae, by the disk diffusion method using Mueller-Hinton agar (MHA). The smaller Ag NPs were found to have significantly higher antibacterial activity. These results showed that Ag NPs can be used as effective growth inhibitors in different biological systems, making them applicable to medical applications. PMID:21674015

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Rustaiyan, Abdolhossein; Ibrahim, Nor Azowa

2011-01-01

250

Shape effects in plasmon resonance of individual colloidal silver nanoparticles  

Microsoft Academic Search

We present a systematic study of the effect of size and shape on the spectral response of individual silver nanoparticles. An experimental method has been developed that begins with the detection and characterization of isolated nanoparticles in the optical far field. The plasmon resonance optical spectrum of many individual nanoparticles are then correlated to their size and shape using high-resolution

J. J. Mock; M. Barbic; D. R. Smith; D. A. Schultz; S. Schultz

2002-01-01

251

Dynamics of colloid silver nanoparticles in an evaporating water drop  

NASA Astrophysics Data System (ADS)

The method of photon correlation spectroscopy is used to investigate the distribution of the diffusion coefficient of silver nanoparticles in an evaporating water drop given that the drop base area remains unchanged (the pinning condition). It is established that the capillary flow dominates over the diffusion nanoparticle motion in redistribution of concentration of the dissolved nanoparticles.

Myslitskaya, N. A.; Khitrin, A. V.; Ivanov, A. M.; Samusev, I. G.; Bryukhanov, V. V.

2012-04-01

252

Separation and measurement of silver nanoparticles and silver ions using magnetic particles.  

PubMed

The recent surge in consumer products and applications using metallic nanoparticles has increased the possibility of human or ecosystem exposure due to unintentional release into the environment. To protect consumer health and the environment, there is an urgent need to develop tools that can characterize and quantify these materials at low concentrations and in complex matrices. In this study, magnetic nanoparticles coated with either dopamine or glutathione were used to develop a new, simple and reliable method for the separation/pre-concentration of trace amounts of silver nanoparticles followed by their quantification using inductively coupled plasma mass spectrometry (ICP-MS). The structurally modified magnetic particles were able to capture trace amounts of silver nanoparticles (~2 ppb) and concentrate (up to 250 times) the particles for analysis with ICP-MS. Under laboratory conditions, recovery of silver nanoparticles was >99%. More importantly, the magnetic particles selectively captured silver nanoparticles in a mixture containing both nano-particulate and ionic silver. This unique feature addresses the challenges of separation and quantification of silver nanoparticles in addition to the total silver in environmental samples. Spiking experiments showed recoveries higher than 97% for tap water and both fresh and saline surface water. PMID:24295749

Mwilu, Samuel K; Siska, Emily; Baig, R B Nasir; Varma, Rajender S; Heithmar, Ed; Rogers, Kim R

2014-02-15

253

Orientation of N-(1-(2-chlorophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide on silver nanoparticles: SERS studies  

NASA Astrophysics Data System (ADS)

In the present study, the silver nanoparticles were synthesized using a solution combustion method with urea as fuel. The prepared silver nanoparticles show an FCC crystalline structure with particle size of 59 nm. FESEM image shows the prepared silver is a rod like structure. The surface-enhanced Raman scattering (SERS) spectrum indicates that the N-(1-(2-chlorophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide (CS) molecule adsorbed on the silver nanoparticles. The spectral analysis reveals that the sulfonamide is adsorbed by tilted orientation on the silver surface. The Hatree Fock calculations were also performed to predict the vibrational motions of CS. This present investigation has been a model system to deduce the interaction of drugs with DNA.

Anuratha, M.; Jawahar, A.; Umadevi, M.; Sathe, V. G.; Vanelle, P.; Terme, T.; Meenakumari, V.; Milton Franklin Benial, A.

2014-10-01

254

Green synthesis of silver and gold nanoparticles using Zingiber officinale root extract and antibacterial activity of silver nanoparticles against food pathogens.  

PubMed

In the present study, we synthesized silver and gold nanoparticles with a particle size of 10-20 nm, using Zingiber officinale root extract as a reducing and capping agent. Chloroauric acid (HAuCl4) and silver nitrate (AgNO3) were mixed with Z. officinale root extract for the production of silver (AgNPs) and gold nanoparticles (AuNPs). The surface plasmon absorbance spectra of AgNPs and AuNPs were observed at 436-531 nm, respectively. Optimum nanoparticle production was achieved at pH 8 and 9, 1 mM metal ion, a reaction temperature 50 °C and reaction time of 150-180 min for AgNPs and AuNPs, respectively. An energy-dispersive X-ray spectroscopy (SEM-EDS) study provides proof for the purity of AgNPs and AuNPs. Transmission electron microscopy images show the diameter of well-dispersed AgNPs (10-20 nm) and AuNPs (5-20 nm). The nanocrystalline phase of Ag and Au with FCC crystal structures have been confirmed by X-ray diffraction analysis. Fourier transform infrared spectroscopy analysis shows the respective peaks for the potential biomolecules in the ginger rhizome extract, which are responsible for the reduction in metal ions and synthesized AgNPs and AuNPs. In addition, the synthesized AgNPs showed a moderate antibacterial activity against bacterial food pathogens. PMID:24668029

Velmurugan, Palanivel; Anbalagan, Krishnan; Manosathyadevan, Manoharan; Lee, Kui-Jae; Cho, Min; Lee, Sang-Myeong; Park, Jung-Hee; Oh, Sae-Gang; Bang, Keuk-Soo; Oh, Byung-Taek

2014-10-01

255

Anticancer activity of Moringa oleifera mediated silver nanoparticles on human cervical carcinoma cells by apoptosis induction.  

PubMed

Silver nanomaterial plays a crucial role in the growing field of nanotechnology as there is an increasing commercial demand for silver nanoparticles (AgNPs) owing to their wide biological applications. The present investigation aims at developing anti-cancerous colloidal silver using Moringa olifera stem bark extract. Electron and atomic force microscopic images were taken to analyze the surface morphology of the synthesized AgNPs. The effects of synthesized AgNPs were tested against human cervical carcinoma cells (HeLa) and cell morphology was further evaluated using 4,6-diamidino-2-phenylindole (DAPI) staining. The efficiency of green synthesized AgNPs was studied with the help of fluorescence activated cell sorting (FACS) and was shown to induce apoptosis through reactive oxygen species (ROS) generation in HeLa cells. PMID:24681047

Vasanth, Karunamoorthy; Ilango, Kaliappan; MohanKumar, Ramasamy; Agrawal, Aruna; Dubey, Govind Prasad

2014-05-01

256

Synthesis and Characterization of Polyethylene Glycol Mediated Silver Nanoparticles by the Green Method  

PubMed Central

The roles of green chemistry in nanotechnology and nanoscience fields are very significant in the synthesis of diverse nanomaterials. Herein, we report a green chemistry method for synthesized colloidal silver nanoparticles (Ag NPs) in polymeric media. The colloidal Ag NPs were synthesized in an aqueous solution using silver nitrate, polyethylene glycol (PEG), and ?-D-glucose as a silver precursor, stabilizer, and reducing agent, respectively. The properties of synthesized colloidal Ag NPs were studied at different reaction times. The ultraviolet-visible spectra were in excellent agreement with the obtained nanostructure studies performed by transmission electron microscopy (TEM) and their size distributions. The Ag NPs were characterized by utilizing X-ray diffraction (XRD), zeta potential measurements and Fourier transform infrared (FT-IR). The use of green chemistry reagents, such as glucose, provides green and economic features to this work. PMID:22837654

Shameli, Kamyar; Ahmad, Mansor Bin; Jazayeri, Seyed Davoud; Sedaghat, Sajjad; Shabanzadeh, Parvaneh; Jahangirian, Hossein; Mahdavi, Mahnaz; Abdollahi, Yadollah

2012-01-01

257

Preparation of solid silver nanoparticles for inkjet printed flexible electronics with high conductivity.  

PubMed

Silver nanoparticles (NPs) which could be kept in solid form and were easily stored without degeneration or oxidation at room temperature for a long period of time were synthesized by a simple and environmentally friendly wet chemistry method in an aqueous phase. Highly stable dispersions of aqueous silver NP inks, sintered at room temperature, for printing highly conductive tracks (?8.0 ?? cm) were prepared simply by dispersing the synthesized silver NP powder in water. These inks are stable, fairly homogeneous and suitable for a wide range of patterning techniques. The inks were successfully printed on paper and polyethylene terephthalate (PET) substrates using a common color printer. Upon annealing at 180 °C, the resistivity of the printed silver patterns decreased to 3.7 ?? cm, which is close to twice that of bulk silver. Various factors affecting the resistivity of the printed silver patterns, such as annealing temperature and the number of printing cycles, were investigated. The resulting high conductivity of the printed silver patterns reached over 20% of the bulk silver value under ambient conditions, which enabled the fabrication of flexible electronic devices, as demonstrated by the inkjet printing of conductive circuits of LED devices. PMID:24337051

Shen, Wenfeng; Zhang, Xianpeng; Huang, Qijin; Xu, Qingsong; Song, Weijie

2014-01-01

258

Green synthesis of silver nanoparticles from aqueous Aegle marmelos leaf extract  

SciTech Connect

Graphical abstract: Silver nanoparticles capped with polyphenols present in Aegle marmelos leaf extract. Display Omitted Highlights: ? Silver nanoparticles are synthesized using Aegle marmelos leaf extract in aqueous media. ? Reduction reaction is fast and occurs at room temperature. ? The presence of polyphenols acts as in situ capping agent. -- Abstract: Synthesis of nanoparticles by green route is an emerging technique drawing more attention recently because of several advantages over the convention chemical routes. The present study reports one-pot synthesis and in situ stabilization of silver nanoparticles using Aegle marmelos leaf extract. Nanoparticles of almost uniform spherical size (?60 nm) were synthesized within ?25 min reaction time at room temperature. The size of particles depends on the ratio of AgNO{sub 3} and leaf extract. The crystallinity, size, and shape of the nanoparticles were characterized by X-ray diffraction, dynamic light scattering, and scanning electron microscopy respectively. The size stability was attained by the capping effect of polyphenolic tannin compound, procatacheuate in the extract. The capped polyphenols can be removed from the particle surface by simple NaOH/methanol wash. The involvement of phenolic compounds in metal ion reduction and capping were supported by UV–visible spectroscopy, infrared spectroscopy, high performance liquid chromatography, and zeta potential measurements.

Jagajjanani Rao, K. [Department of Chemical Engineering, National Institute of Technology, Rourkela 769 008, Orissa (India)] [Department of Chemical Engineering, National Institute of Technology, Rourkela 769 008, Orissa (India); Paria, Santanu, E-mail: santanuparia@yahoo.com [Department of Chemical Engineering, National Institute of Technology, Rourkela 769 008, Orissa (India)] [Department of Chemical Engineering, National Institute of Technology, Rourkela 769 008, Orissa (India)

2013-02-15

259

Synthesis of eco-friendly silver nanoparticles from Morinda tinctoria leaf extract and its larvicidal activity against Culex quinquefasciatus.  

PubMed

Mosquitoes are the major vector for the transmission of malaria, dengue fever, yellow fever, filariasis, chikungunya and Japanese encephalitis, and they accounted for global mortality and morbidity with increased resistance to common insecticides. The aim of this study was to investigate the larvicidal potential of the acetone leaf extracts of Morinda tinctoria and synthesized silver nanoparticles against third instar larvae of Culex quinquefasciatus Say (Diptera: Culicidae). Nanoparticles are being used in many commercial applications. It was found that aqueous silver ions can be reduced by aqueous extract of plant parts to generate extremely stable silver nanoparticles in water. Synthesized AgNPs were characterized by ultraviolet-visible (UV-vis) spectroscopy, Atomic force microscopy (AFM) and Fourier transform infrared spectroscopy (FT-IR) analysis. The synthesized silver nanoparticles have also been tested against the third instar larvae of C. quinquefasciatus. The leaf extract and the AgNPs high mortality values were 50 % lethal concentration (LC50)?=?8.088 and 1.442 ppm against C. quinquefasciatus, respectively. The results recorded from ultraviolet-visible spectroscopy, atomic force microscopy and Fourier transform infrared spectroscopy support the biosynthesis and characterization of silver nanoparticles. These results suggest that the leaf extract of M. tinctoria and synthesis of AgNPs have the potential to be used as an ideal eco-friendly approach for the control of C. quinquefasciatus. By this approach, it is suggestive that this rapid synthesis of nanoparticles would be proper for developing a biological process for mosquito control. PMID:25373452

Kumar, K Ramesh; Nattuthurai, N; Gopinath, Ponraj; Mariappan, Tirupathi

2015-02-01

260

Preparation of silver nanoparticle containing silica micro beads and investigation of their antibacterial activity  

NASA Astrophysics Data System (ADS)

Silver nanoparticle containing silica micro beads (Ag-NPBs) were successfully prepared by using sodium silicate, a cheap precursor, involving chemical reductive method. First, silica gel was synthesized and crushed into micro beads which have sizes ranging from 0.5 to 1 mm. Silica micro beads were then modified with 3-aminopropyltriethoxysilane to graft amino functional groups onto their surface. Silver ions were loaded onto the surface of the modified silica and reduced to silver crystal by adding NaBH 4. The presence of silver nanoparticles as well as structure of materials was characterized with FT-IR, XRD, BET, FE-SEM, TEM, UV-vis spectrophotometer, and optical microscope. Silver nanoparticles with an average size about 5 nm were found in the pore and on the surface of amino functionalized silica beads. Ag-NPBs samples were tested for their antibacterial activity against Escherichia coli ( E. coli). The antibacterial activity was examined by both zone inhibition and test tube test method. Biological results indicated that the synthesized materials have an excellent antibacterial performance against E. coli which was completely inhibited after 5 min contact with Ag-NPBs.

Quang, Dang Viet; Sarawade, Pradip B.; Hilonga, Askwar; Kim, Jong-Kil; Chai, Young Gyu; Kim, Sang Hoon; Ryu, Jae-Yong; Kim, Hee Taik

2011-05-01

261

Non-hazardous anticancerous and antibacterial colloidal 'green' silver nanoparticles.  

PubMed

Poly(ethylene glycol) stabilized colloidal silver nanoparticles were prepared using the reductive potency of the aqueous extract of Thuja occidentalis leaves under ambient conditions. The nanoparticles were well dispersed within a narrow size spectrum (7-14 nm) and displayed characteristic surface plasmon resonance peak at around 420 nm and Bragg's reflection planes of fcc structure. MTT assay revealed the dose-dependent cytocompatibility and toxicity of the nanoparticles with the L929 normal cell line. On the other hand, the antiproliferative action of the nanoparticles was evaluated on HeLa cell (cancerous cells) line. Fluorescence and phase contrast microscopic imaging indicated the appearance of multinucleate stages with aggregation and nuclear membrane disruption of the HeLa cells post treatment with the nanoparticles. The interaction at the prokaryotic level was also assessed via differential antibacterial efficacy against Staphylococcus aureus (MTCC 3160) and Escherichia coli (MTCC 40). Under these perspectives, it is also necessary to observe the environmental impact of the prepared silver nanoparticles. Hence, the dose dependent toxicity of silver nanoparticles was evaluated upon the earthworm species Eisenia fetida. Neither the survival nor the reproduction was affected by the addition of silver nanoparticles up to 1000 ppm. Thus these 'green' silver nanoparticles have promising potential as future materials. PMID:23352940

Barua, Shaswat; Konwarh, Rocktotpal; Bhattacharya, Satya Sundar; Das, Pallabi; Devi, K Sanjana P; Maiti, Tapas K; Mandal, Manabendra; Karak, Niranjan

2013-05-01

262

Malva parviflora extract assisted green synthesis of silver nanoparticles  

NASA Astrophysics Data System (ADS)

Five plant leaf extracts (Malva parviflora, Beta vulgaris subsp. Vulgaris, Anethum graveolens, Allium kurrat and Capsicum frutescens) were screened for their bioreduction behavior for synthesis of silver nanoparticles. M. parviflora (Malvaceae) was found to exhibit the best reducing and protecting action in terms of synthesis rate and monodispersity of the prepared silver nanoparticles. Our measurements indicate that biosynthesis of Ag nanoparticles by M. parviflora produces Ag nanoparticles with the diameters in the range of 19-25 nm. XRD studies reveal a high degree of crystallinity and monophasic Ag nanoparticles of face-centered cubic structure. FTIR analysis proved that particles are reduced and stabilized in solution by the capping agent that is likely to be proteins secreted by the biomass. The present process is an excellent candidate for the synthesis of silver nanoparticles that is simple, easy to perform, pollutant free and inexpensive.

Zayed, Mervat F.; Eisa, Wael H.; Shabaka, A. A.

2012-12-01

263

Synthesis of monodisperse, quasi-spherical silver nanoparticles with sizes defined by the nature of silver precursors.  

PubMed

Monodisperse, quasi-spherical silver nanoparticles (Ag NPs) with controlled sizes have been produced directly in water via adding the aqueous solutions of the mixtures of AgNO3 and sodium citrate to boiling aqueous solutions of ascorbic acid (AA). Different compounds, including NaCl, NaBr, KI, Na2SO4, Na2CO3, Na2S, and Na3PO4, are added to the AgNO3/citrate mixture solutions to form new silver compounds with fairly low solubility in water, which are used as precursors instead of soluble Ag(+) ions to synthesize Ag NPs via AA/citrate reduction. This enables us not only to produce monodisperse, quasi-spherical Ag NPs but also to tune the sizes of the resulting NPs from 16 to 30 nm according to the potential of new silver precursors as well as the concentrations of anions. PMID:24528373

Li, Houshen; Xia, Haibing; Ding, Wenchao; Li, Yijing; Shi, Qiurong; Wang, Dayang; Tao, Xutang

2014-03-11

264

Powerful colloidal silver nanoparticles for the prevention of gastrointestinal bacterial infections  

NASA Astrophysics Data System (ADS)

In this work we have demonstrated a powerful disinfectant ability of colloidal silver nanoparticles (NPs) for the prevention of gastrointestinal bacterial infections. The silver NPs colloid was synthesized by a UV-enhanced chemical precipitation. Two gastrointestinal bacterial strains of Escherichia coli (ATCC 43888-O157:k-:H7) and Vibrio cholerae (O1) were used to verify the antibacterial activity of the as-prepared silver NPs colloid by means of surface disinfection assay in agar plates and turbidity assay in liquid media. Transmission electron microscopy was also employed to analyze the ultrastructural changes of bacterial cells caused by silver NPs. Noticeably, our silver NPs colloid displayed a highly effective bactericidal effect against two tested gastrointestinal bacterial strains at a silver concentration as low as ?3 mg l?1. More importantly, the silver NPs colloid showed an enhancement of antibacterial activity and long-lasting disinfectant effect as compared to conventional chloramin B (5%) disinfection agent. These advantages of the as-prepared colloidal silver NPs make them very promising for environmental treatments contaminated with gastrointestinal bacteria and other infectious pathogens. Moreover, the powerful disinfectant activity of silver-containing materials can also help in controlling and preventing further outbreak of diseases.

Le, Anh-Tuan; Tam Le, Thi; Quy Nguyen, Van; Hoang Tran, Huy; Dang, Duc Anh; Tran, Quang Huy; Vu, Dinh Lam

2012-12-01

265

Silver Nanoparticles Obtained by Laser Ablation Using Different Stabilizers  

NASA Astrophysics Data System (ADS)

We have synthesized silver nanoparticles by laser ablation in water using three stabilizers: hexadecyltrimethylammonium (CTAB) surfactant, polyamidoamine dendrimer second generation (PAMAM 2G) and polyamidoamine dendrimer fourth generation (PAMAM 4G) at different concentrations. We obtained spherical nanoparticles with narrow size distributions and average sizes ranging from 6 to 20 nm depending on the type of stabilizer and its concentration. For all cases the highest stabilizer concentration yielded the lowest average particle size; 15.5, 9.5, and 5.6 nm for CTAB, PAMAM 2G and PAMAM 4G respectively. We have also studied the stability of the nanoparticle colloids over a period of 30 days. Only the colloids of CTAB 10-3 M, all the concentrations of PAMAM 4G and pure water were stable after this time. This is explained in terms of steric hindrance of the stabilizer molecules and particle charge from Zeta potential measurements. All the results from transmission electron microscopy correlate well with those observed from the ultraviolet and visible spectra of each sample in terms of absorbance, peak width and peak maximum.

Olea-Mejía, Oscar; Pote-Orozco, Héctor; Camacho-López, Marco A.; Olea-Cardoso, Oscar; López-Castañares, Rafael; Vilchis-Néstor, Alfredo R.

2013-11-01

266

Silver nanoparticle-embedded polymersome nanocarriers for the treatment of antibiotic-resistant infections.  

PubMed

The rapidly diminishing number of effective antibiotics that can be used to treat infectious diseases and associated complications in a physician's arsenal is having a drastic impact on human health today. This study explored the development and optimization of a polymersome nanocarrier formed from a biodegradable diblock copolymer to overcome bacterial antibiotic resistance. Here, polymersomes were synthesized containing silver nanoparticles embedded in the hydrophobic compartment, and ampicillin in the hydrophilic compartment. Results showed for the first time that these silver nanoparticle-embedded polymersomes (AgPs) inhibited the growth of Escherichia coli transformed with a gene for ampicillin resistance (bla) in a dose-dependent fashion. Free ampicillin, AgPs without ampicillin, and ampicillin polymersomes without silver nanoparticles had no effect on bacterial growth. The relationship between the silver nanoparticles and ampicillin was determined to be synergistic and produced complete growth inhibition at a silver-to-ampicillin ratio of 1?:?0.64. In this manner, this study introduces a novel nanomaterial that can effectively treat problematic, antibiotic-resistant infections in an improved capacity which should be further examined for a wide range of medical applications. PMID:25628231

Geilich, Benjamin M; van de Ven, Anne L; Singleton, Gloria L; Sepúlveda, Liuda J; Sridhar, Srinivas; Webster, Thomas J

2015-02-12

267

Green Synthesis of Silver Nanoparticles Using Cycas Leaf  

Microsoft Academic Search

A green, low-cost, and reproducible Cycas leaf–negotiated synthesis of silver nanoparticles is reported. X-ray and transmission electron microscopy (TEM) analyses are performed to ascertain the formation of Ag nanoparticles. Nanoparticles almost spherical in shape having the size of 2–6 nm are found. Rietveld analysis to the X-ray data indicated that Ag nanoparticles have fcc unit cell structure. Ultraviolet (UV)-visible study

Anal K. Jha; K. Prasad

2010-01-01

268

Silver nanoparticle structures realized by digital surface micromachining  

E-print Network

We report a new surface micromachining process using commercial silver nanoparticle inks and digital fabrication methods. This process is entirely digital (non-lithographic patterning), the feature sizes can be <20 mum, ...

Schmidt, Martin Arnold

269

Facile preparation of silver nanoparticles immobilized on chitin nanofiber surfaces to endow antifungal activities.  

PubMed

Silver nanoparticles were prepared on chitin nanofiber surfaces by UV light reduction of silver ions. The chitin nanofibers could be efficient substrates to immobilize silver nanoparticles with stable dispersion states. The dispersion and the nanocomposite film with acrylic resin showed characteristic absorption property in the visible light region due to the effect of the silver nanoparticles. Silver nanoparticles endowed strong antifungal activity to chitin nanofibers. PMID:25498704

Ifuku, Shinsuke; Tsukiyama, Yui; Yukawa, Taisuke; Egusa, Mayumi; Kaminaka, Hironori; Izawa, Hironori; Morimoto, Minoru; Saimoto, Hiroyuki

2015-03-01

270

Silver Nanoparticles Part 1: Synthesis and Spectroscopy  

NSDL National Science Digital Library

The NACK Center is an organization committed to supporting two âÂÂyear degree programs in micro and nanotechnology. The center offers online educational material for curriculum enhancement in this subject field. One of these resources is a lab documentation focusing on the topic of silver nanoparticles. The lab is "designed for an advanced chemistry class, but may also be done with first year student. Prior experience with spectroscopy is recommended.â The lesson includes objectives, sample solution preparations, and sample data and calculations. Overall, the objectives of this lesson are to demonstrate the use of a spectrophotometer, the observation of nanoscale physical properties and conversion of different unit measurements. The site requires a free log-in for access to the material.

2010-03-31

271

Green and Rapid Synthesis of Anticancerous Silver Nanoparticles by Saccharomyces boulardii and Insight into Mechanism of Nanoparticle Synthesis  

PubMed Central

Rapidly developing field of nanobiotechnology dealing with metallic nanoparticle (MNP) synthesis is primarily lacking control over size, shape, dispersity, yield, and reaction time. Present work describes an ecofriendly method for the synthesis of silver nanoparticles (AgNPs) by cell free extract (CFE) of Saccharomyces boulardii. Parameters such as culture age (stationary phase growth), cell mass concentration (400?mg/mL), temperature (35°C), and reaction time (4?h), have been optimized to exercise a control over the yield of nanoparticles and their properties. Nanoparticle (NP) formation was confirmed by UV-Vis spectroscopy, elemental composition by EDX (energy dispersive X-rays) analysis, and size and shape by transmission electron microscopy. Synthesized nanoparticles had the size range of 3–10?nm with high negative zeta potential (?31?mV) indicating excellent stability. Role of proteins/peptides in NP formation and their stability were also elucidated. Finally, anticancer activity of silver nanoparticles as compared to silver ions was determined on breast cancer cell lines. PMID:24298556

Kaler, Abhishek; Jain, Sanyog; Banerjee, Uttam Chand

2013-01-01

272

Green synthesis of protein capped silver nanoparticles from phytopathogenic fungus Macrophomina phaseolina (Tassi) Goid with antimicrobial properties against multidrug-resistant bacteria  

NASA Astrophysics Data System (ADS)

In recent years, green synthesis of nanoparticles, i.e., synthesizing nanoparticles using biological sources like bacteria, algae, fungus, or plant extracts have attracted much attention due to its environment-friendly and economic aspects. The present study demonstrates an eco-friendly and low-cost method of biosynthesis of silver nanoparticles using cell-free filtrate of phytopathogenic fungus Macrophomina phaseolina. UV-visible spectrum showed a peak at 450 nm corresponding to the plasmon absorbance of silver nanoparticles. Scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM) revealed the presence of spherical silver nanoparticles of the size range 5 to 40 nm, most of these being 16 to 20 nm in diameter. X-ray diffraction (XRD) spectrum of the nanoparticles exhibited 2 ? values corresponding to silver nanoparticles. These nanoparticles were found to be naturally protein coated. SDS-PAGE analysis showed the presence of an 85-kDa protein band responsible for capping and stabilization of the silver nanoparticles. Antimicrobial activities of the silver nanoparticles against human as well as plant pathogenic multidrug-resistant bacteria were assayed. The particles showed inhibitory effect on the growth kinetics of human and plant bacteria. Furthermore, the genotoxic potential of the silver nanoparticles with increasing concentrations was evaluated by DNA fragmentation studies using plasmid DNA.

Chowdhury, Supriyo; Basu, Arpita; Kundu, Surekha

2014-07-01

273

Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli  

PubMed Central

Vibrio cholerae and enterotoxic Escherichia coli (ETEC) remain two dominant bacterial causes of severe secretory diarrhea and still a significant cause of death, especially in developing countries. In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves. We characterized the quantity and quality of nanoparticles by UV–visible wavelength scans and nanoparticle tracking analysis. Nanoparticles could be synthesized in reproducible yields of approximately 108 particles/ml with mode particles sizes of approx. 90–100 nm. Antibacterial activity against two pathogens was assessed by minimal inhibitory concentration assays and survival curves. Both pathogens exhibited similar resistance profiles with minimal inhibitory concentrations ranging between 5 × 105 and 107 particles/ml. Interestingly, zinc nanoparticles showed a slightly higher efficacy, but sublethal concentrations caused adverse effects and resulted in increased biofilm formation of V. cholerae. Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity. This consequently deceases the levels of this second messenger, which is a known inhibitor of biofilm formation. Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively. PMID:25466205

Salem, Wesam; Leitner, Deborah R.; Zingl, Franz G.; Schratter, Gebhart; Prassl, Ruth; Goessler, Walter; Reidl, Joachim; Schild, Stefan

2015-01-01

274

Antibacterial activity of silver and zinc nanoparticles against Vibrio cholerae and enterotoxic Escherichia coli.  

PubMed

Vibrio cholerae and enterotoxic Escherichia coli (ETEC) remain two dominant bacterial causes of severe secretory diarrhea and still a significant cause of death, especially in developing countries. In order to investigate new effective and inexpensive therapeutic approaches, we analyzed nanoparticles synthesized by a green approach using corresponding salt (silver or zinc nitrate) with aqueous extract of Caltropis procera fruit or leaves. We characterized the quantity and quality of nanoparticles by UV-visible wavelength scans and nanoparticle tracking analysis. Nanoparticles could be synthesized in reproducible yields of approximately 10(8)particles/ml with mode particles sizes of approx. 90-100nm. Antibacterial activity against two pathogens was assessed by minimal inhibitory concentration assays and survival curves. Both pathogens exhibited similar resistance profiles with minimal inhibitory concentrations ranging between 5×10(5) and 10(7)particles/ml. Interestingly, zinc nanoparticles showed a slightly higher efficacy, but sublethal concentrations caused adverse effects and resulted in increased biofilm formation of V. cholerae. Using the expression levels of the outer membrane porin OmpT as an indicator for cAMP levels, our results suggest that zinc nanoparticles inhibit adenylyl cyclase activity. This consequently deceases the levels of this second messenger, which is a known inhibitor of biofilm formation. Finally, we demonstrated that a single oral administration of silver nanoparticles to infant mice colonized with V. cholerae or ETEC significantly reduces the colonization rates of the pathogens by 75- or 100-fold, respectively. PMID:25466205

Salem, Wesam; Leitner, Deborah R; Zingl, Franz G; Schratter, Gebhart; Prassl, Ruth; Goessler, Walter; Reidl, Joachim; Schild, Stefan

2015-01-01

275

Fluorescence quenching and photocatalytic degradation of textile dyeing waste water by silver nanoparticles  

NASA Astrophysics Data System (ADS)

Silver nanoparticles (Ag NPs) of different sizes have been prepared by chemical reduction method and characterized using UV-vis spectroscopy and transmission electron microscopy (HRTEM). Fluorescence spectral analysis showed that the quenching of fluorescence of textile dyeing waste water (TDW) has been found to decrease with decrease in the size of the Ag NPs. Experimental results show that the silver nanoparticles can quench the fluorescence emission of adsorbed TDW effectively. The fluorescence interaction between Ag NPs (acceptor) and TDW (donor) confirms the Förster Resonance Energy Transfer (FRET) mechanism. Long range dipole-dipole interaction between the excited donor and ground state acceptor molecules is the dominant mechanism responsible for the energy transfer. Furthermore, photocatalytic degradation of TDW was measured spectrophotometrically by using silver as nanocatalyst under UV light illumination. The kinetic study revealed that synthesized Ag NPs was found to be effective in degrading TDW.

Kavitha, S. R.; Umadevi, M.; Janani, S. R.; Balakrishnan, T.; Ramanibai, R.

2014-06-01

276

Bioactive compound loaded stable silver nanoparticle synthesis from microwave irradiated aqueous extracellular leaf extracts of Naringi crenulata and its wound healing activity in experimental rat model.  

PubMed

An efficient and eco-friendly protocol for the synthesis of bioactive silver nanoparticles was developed using Naringi crenulata leaf extracts via microwave irradiation method. Silver nanoparticles were synthesized by treating N. crenulata leaf extracts with 1mM of aqueous silver nitrate solution. An effective bioactive compound such as alkaloids, phenols, saponins and quinines present in the N. crenulata reduces the Ag(+) into Ag(0). The synthesized silver nanoparticles were monitored by UV-vis spectrophotometer and further characterized by X-ray diffraction (XRD), Fourier Transform Infra Red (FTIR), Energy-dispersive X-ray spectroscopy (EDX) and field emission scanning electron microscopy (FESEM). UV-vis spectroscopy showed maximum absorbance at 390nm due to surface plasmon resonance of AgNPs. From FESEM results, an average crystal size of the synthesized nanoparticle was 72-98nm. FT-IR results showed sharp absorption peaks and they were assigned to phosphine, alkyl halides and sulfonate groups. Silver nanoparticles synthesized were generally found to be spherical and cubic shape. Topical application of ointment prepared from silver nanoparticles of N. crenulata were formulated and evaluated in vivo using the excision wound healing model on Wistar albino rats. The measurement of the wound areas was performed on 3rd, 6th, 9th, 12th and 15th days and the percentage of wound closures was calculated accordingly. By the 15th day, the ointment base containing 5% (w/w) of silver nanoparticles showed 100% wound healing activity compared with that of the reference as well as control bases. The results strongly suggested that the batch C ointment containing silver nanaoparticles synthesized from the leaf extracts of N. crenulata was found to be very effective in wound repair and encourages harnessing the potentials of the plant biomolecules loaded silver nanoparticle in the treatment of tropical diseases including wound healing. PMID:24681224

Bhuvaneswari, T; Thiyagarajan, M; Geetha, N; Venkatachalam, P

2014-07-01

277

Poly(ethylene) glycol-capped silver and magnetic nanoparticles: synthesis, characterization, and comparison of bactericidal and cytotoxic effects.  

PubMed

Silver and magnetic (Fe3O4) nanoparticles have attracted wide attention as novel antimicrobial agents due to their unique chemical and physical properties. In order to study the comparative effects on antibacterial and animal cytotoxicity, Staphylococcus aureus and NIH 3T3 fibroblasts were used, respectively. Both nanoparticles were synthesized via a novel matrix-mediated method using poly(ethylene) glycol. Formation of silver nanoparticles was confirmed by fluorescence and ultraviolet-visible spectroscopic techniques. The poly(ethylene) glycol-coated silver and Fe3O4 nanoparticles were characterized by scanning electron microscope, transmission electron microscope, zeta potential, particle size analysis, Fourier-transform infrared, X-ray diffraction, and X-ray photoelectron spectroscopy. The antimicrobial results indicate that both poly(ethylene) glycol-coated silver and Fe3O4 nanoparticles inhibited S. aureus growth at the concentrations of 5 and 10?µg/mL at all time points without showing any significant cytotoxicity on NIH 3T3 fibroblasts. The particle size of both the poly(ethylene) glycol-coated silver and Fe3O4 nanoparticles dominated in the range 10-15?nm, obtained by particle size analyzer. The poly(ethylene) glycol coating on the particles showed less aggregation of nanoparticles, as observed by scanning electron microscope and transmission electron microscope. The overall obtained results indicated that these two nanoparticles were stable and could be used to develop a magnetized antimicrobial scaffolds for biomedical applications. PMID:23959858

Mandal, A; Sekar, S; Chandrasekaran, N; Mukherjee, A; Sastry, T P

2013-11-01

278

LL37 peptide@silver nanoparticles: combining the best of the two worlds for skin infection control.  

PubMed

Capping silver nanoparticles with LL37 peptide eradicates the antiproliferative effect of silver on primary skin cells, but retains the bactericidal properties of silver nanoparticles with activities comparable to silver nitrate or silver sulfadiazine. In addition, LL37 capped silver nanoparticles have anti-biofilm formation activity. PMID:24789474

Vignoni, Mariana; de Alwis Weerasekera, Hasitha; Simpson, Madeline J; Phopase, Jaywant; Mah, Thien-Fah; Griffith, May; Alarcon, Emilio I; Scaiano, Juan C

2014-06-01

279

Toxicity mechanisms in Escherichia coli vary for silver nanoparticles and differ from ionic silver.  

PubMed

Silver nanoparticles (Ag NPs) are commonly added to various consumer products and materials to impair bacterial growth. Recent studies suggested that the primary mechanism of antibacterial action of silver nanoparticles is release of silver ion (Ag(+)) and that particle-specific activity of silver nanoparticles is negligible. Here, we used a genome-wide library of Escherichia coli consisting of ?4000 single gene deletion mutants to elucidate which physiological pathways are involved in how E. coli responds to different Ag NPs. The nanoparticles studied herein varied in both size and surface charge. AgNO3 was used as a control for soluble silver ions. Within a series of differently sized citrate-coated Ag NPs, smaller size resulted in higher Ag ion dissolution and toxicity. Nanoparticles functionalized with cationic, branched polyethylene imine (BPEI) exhibited equal toxicity with AgNO3. When we used a genome-wide approach to investigate the pathways involved in the response of E. coli to different toxicants, we found that only one of the particles (Ag-cit10) exhibited a pattern of response that was statistically similar to that of silver ion. By contrast, the pathways involved in E. coli response to Ag-BPEI particles were more similar to those observed for another cationic nanoparticle that did not contain Ag. Overall, we found that the pathways involved in bacterial responses to Ag nanoparticles are highly dependent on physicochemical properties of the nanoparticles, particularly the surface characteristics. These results have important implications for the regulation and testing of silver nanoparticles. PMID:24341736

Ivask, Angela; Elbadawy, Amro; Kaweeteerawat, Chitrada; Boren, David; Fischer, Heidi; Ji, Zhaoxia; Chang, Chong Hyun; Liu, Rong; Tolaymat, Thabet; Telesca, Donatello; Zink, Jeffrey I; Cohen, Yoram; Holden, Patricia Ann; Godwin, Hilary A

2014-01-28

280

Chemiluminescent Reactions Catalyzed by Nanoparticles of Gold, Silver, and Gold/Silver Alloys  

NASA Astrophysics Data System (ADS)

Chemiluminescence (CL) reactions are catalyzed by metals nanoparticles, which display unique catalytic properties due to an increased surface area. The present study describes the catalytic effects of nanoparticles (NP) of silver, gold, and alloys of Au/Ag nanoparticles on the chemiluminescent reaction taking place between luminol and potassium ferricyanide. It was found that silver nanoparticles and alloy nanoparticles enhance the CL process when their sizes remained in the range of 30 nm to 50 nm. The data show that the intensity and rate of chemiluminescence were influenced by the mole fraction of gold and silver in the alloy. Data to this chemiluminescence reaction are modeled by a double exponential curve, which indicates that two competing processes are occurring.

Abideen, Saqib Ul

281

Less is more, greener microbial synthesis of silver nanoparticles.  

PubMed

Microbial nano-synthesis has been well established as a green method for the sustainable development of nanotechnology. However, the mechanism of this biotechnology has to be reconsidered with the increasing realization that microorganism culture broth plays a vital role during the synthesis, which may obviate the dependence on microbes. Here, we demonstrate that silver nanoparticles (AgNPs) could be synthesized in several types of microorganism culture broth (an aqueous solution abundant in peptone, yeast extract from Saccharomyces cerevisiae, dextrose and other reducing and stabilizing agents) without any specific living microbe involvement. Light and high pH values of broth were identified as two critical factors in ensuring pure AgNPs formation. In broths containing NaCl at high concentration (0.5wt%), silver chloride was identified as the major intermediate and could be converted to AgNPs via one-pot photoreduction. Our broth alone strategy dramatically simplifies the conventional microbial nano-synthesis process by cutting the use of microorganisms and thus provides a more eco-friendly way for nano-Ag preparation. The fundamental understanding of the microbial synthesis mechanisms and implementing of complete green methods to fabricate technologically important nanomaterials will be further promoted by this study. PMID:25442949

Liu, Lihong; Liu, Tingting; Tade, Moses; Wang, Shaobin; Li, Xinyong; Liu, Shaomin

2014-12-01

282

Radiolytically induced formation and optical absorption spectra of colloidal silver nanoparticles in supercritical ethane.  

SciTech Connect

Colloidal silver nanoparticles were synthesized in supercritical ethane at 80 {sup o}C and 80-120 bar, with methanol as cosolvent. Solvated electrons, produced by a pulse of 20 MeV electrons, reduced the silver ions. The time-resolved technique of pulse radiolysis was employed to characterize the reduction products and colloidal metallic particles. The absorption spectra of small silver clusters (Ag{sub 2}{sup +}, Ag{sub 3}{sup +}, Ag{sub 4}{sup 2+}, etc.) were detected at short times after the pulse. Colloidal metallic silver particles were identified by their characteristic plasmon absorption at 1-10 s after the pulse. Colloidal particles are stable for hours in supercritical ethane. The particles are less than 10 nm in diameter. Their size was determined using transmission electron microscope after precipitation from the solution.

Dimitrijevic, N. M.; Bartels, D. M.; Jonah, C. D.; Takahashi, K.; Rajh, T.; Chemistry

2001-02-08

283

Synthesis and Catalytic Activity of Pluronic Stabilized Silver-Gold Bimetallic Nanoparticles  

PubMed Central

In this report, we demonstrate a rapid, simple, and green method for synthesizing silver-gold (Ag-Au) bimetallic nanoparticles (BNPs). We used a novel modification to the galvanic replacement reaction by suspending maltose coated silver nanoparticles (NPs) in ? 2% aqueous solution of EO100PO65EO100 (Pluronic F127) prior to HAuCl4 addition. The Pluronic F127 stabilizes the BNPs, imparts biocompatibility, and mitigates the toxicity issues associated with other surfactant stabilizers. BNPs with higher Au:Ag ratios and, subsequently, different morphologies were successfully synthesized by increasing the concentration of gold salt added to the Ag NP seeds. These BNPs have enhanced catalytic activities than typically reported for monometallic Au or Ag NPs (? 2–10 fold) of comparable sizes in the sodium borohydride reduction of 4-nitrophenol. The 4-nitrophenol reduction rates were highest for partially hollow BNP morphologies. PMID:25580244

Holden, Megan S.; Nick, Kevin E.; Hall, Mia; Milligan, Jamie R.; Chen, Qiao; Perry, Christopher C.

2014-01-01

284

Thermal conductivity studies of novel nanofluids based on metallic silver decorated mesoporous silica nanoparticles  

SciTech Connect

Graphical abstract: - Highlights: • Metallic silver was decorated in mSiO{sub 2} with grafted hemiaminal functional groups. • Synthesized nanoparticles were used for preparation of glycerol based nanofluids. • The effect of temperature, weight fraction of mSiO{sub 2} and concentration of silver nanoparticles on thermal conductivity of nanofluids was investigated. - Abstract: In the present study, the mesoporous structure of silica (mSiO{sub 2}) nanoparticles as well as hemiaminal grafted mSiO{sub 2} decorated by metallic silver (Ag/mSiO{sub 2}) has been used for the preparation of glycerol based nanofluids. Structural and morphological characterization of the synthesized products have been carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), UV–vis spectroscopy, inductively coupled plasma (ICP) and N{sub 2} adsorption–desorption isotherms. The thermal conductivity and viscosity of the nanofluids have been measured as a function of temperature for various weight fractions and silver concentrations of mSiO{sub 2} and Ag/mSiO{sub 2} nanoparticles, respectively. The results show that the thermal conductivity of the nanofluids increase up to 9.24% as the weight fraction of mSiO{sub 2} increases up to 4 wt%. Also, increasing the percent of the silver decorated mSiO{sub 2} (Ag/mSiO{sub 2}) up to 2.98% caused an enhancement in the thermal conductivity of the base fluid up to 10.95%. Furthermore, the results show that the nanofluids have Newtonian behavior in the tested temperature range for various concentrations of nanoparticles.

Tadjarodi, Azadeh, E-mail: tajarodi@iust.ac.ir [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Zabihi, Fatemeh [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Chemistry and Nanotechnology Laboratory, National Center for Laser Science and Technology, Tehran (Iran, Islamic Republic of)

2013-10-15

285

Second harmonic generation from silver nanoparticles in aqueous solution with different protective agents  

NASA Astrophysics Data System (ADS)

Nanometer-sized metallic colloidal particles with plasmonic resonances in the visible range are widely investigated for their attractive optical properties as sensors, for imaging and cancer treatment. Their second-order nonlinear optical properties are remarkably high. In this work, silver colloidal solutions have been synthesized by a simple and quick method in aqueous solutions with different protective agents (PVA, PVP). The first hyperpolarizability ? values of Ag per atom and per particle for nanospheres at 1064 nm have been measured. Silver nanoparticles, which possess intense visible region surface plasmon absorption bands, prove to be excellent nonlinear scatterers.

Ngo, Hoang M.; Ledoux-Rak, Isabelle

2014-08-01

286

Green synthesis of silver nanoparticles from Gloriosa superba L. leaf extract and their catalytic activity  

NASA Astrophysics Data System (ADS)

The present work focuses the use of aqueous extract of Gloriosa superba Linn. (Glory Lily) for producing silver nanoparticles (AgNPs) from silver nitrate aqueous solution. Phytochemical analysis of the extract revealed the presence of alkaloid, amino acids, carbohydrates and proteins in the extract and they serve as effective reducing and capping agents for converting silver nitrate to silver nanoparticles. The nanoparticles were characterised by UV (Ultra violet), FT-IR (Fourier Transform Infrared), XRD (X-ray diffraction), TEM (Transmission Electron Microscope) SEM-EDX (Scanning Electron Microscopy-Energy Dispersive X-ray), and PL (Photoluminescence) studies. Moreover, the catalytic activity of synthesized AgNPs in the reduction of methylene blue was studied by UV-vis spectrophotometer. The synthesized AgNPs are observed to have a good catalytic activity on the reduction of methylene blue by G. superba extract which is confirmed by the decrease in absorbance maximum values of methylene blue with respect to time using UV-vis spectrophotometer.

Ashokkumar, S.; Ravi, S.; Velmurugan, S.

2013-11-01

287

Adsorption of N-(1-(2-bromophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide on silver nanoparticles: SERS investigation.  

PubMed

SERS provides essential data regarding the interaction of molecules in drugs with DNA. In the present study silver nanoparticles were synthesized using a solution combustion method with urea as fuel. The prepared silver nanoparticles are rod like structure. Surface-enhanced Raman scattering (SERS) of N-(1-2-bromophenyl)-2-(2-nitrophenyl)ethyl)-4-methylbenzenesulfonamide (BrS) adsorbed on the silver nanoparticle was studied. The nRs and Raman spectral analysis reveal that the BrS adsorbed tilted orientation on the silver surface. Vibrational modes of nRs along with HF calculations are also performed to study the HOMO and LUMO behavior and vibrational features of BrS. PMID:25498819

Anuratha, M; Jawahar, A; Umadevi, M; Sathe, V G; Vanelle, P; Terme, T; Khoumeri, O; Meenakumari, V; Milton Franklin Benial, A

2015-03-01

288

Preparation of mono-dispersed silver nanoparticles assisted by chitosan-g-poly(?-caprolactone) micelles and their antimicrobial application  

NASA Astrophysics Data System (ADS)

Amphiphilic chitosan-graft-poly(?-caprolactone) (CS-g-PCLs) copolymers were synthesized by a homogeneous coupling method and characterized by 1H NMR, FTIR and ninhydrin assay. The graft copolymers were subsequently self-assembled into micelles, which were measured by DLS and TEM. The particle size of the micelles decreased as the segment grafting fraction was increased. Thereafter, silver nanoparticles were prepared in the presence of chitosan-based micelles under UV irradiation. The molar ratio and radiation time of silver to micelles were optimized with process monitored via UV-vis spectrophotometer. DLS and TEM were used to illustrate the particle structure and size while XRD patterns were applied to characterize the crystal structures of polymer-assisted silver nanoparticles. Films impregnated with silver nanoparticles were conducted with results of strong antimicrobial activities against Escherichia coli and Staphylococcus aureus as model Gram-negative and positive bacteria.

Gu, Chunhua; Zhang, Huan; Lang, Meidong

2014-05-01

289

Composition-Controlled Synthesis of Bimetallic Gold-Silver Nanoparticles  

SciTech Connect

This paper reports finding of an investigation of the synthesis of monolayer-capped binary gold-silver bimetallic nanoparticles that is aimed at understanding the control factors governing the formation of the bimetallic compositions. The findings have important implications to the exploration of gold-based bimetallic nanoparticles for biosensing and fuell cell catalytic nanomaterials.

Kariuki, Nancy N.; Luo, Jin; Maye, Mathew M.; Hassan, Syed A.; Menard, Tanya; Naslund, H. R.; Lin, Yuehe; Wang, Chong M.; Engelhard, Mark H.; Zhong, Chuan-Jian

2004-12-07

290

Size-controlled green synthesis of silver nanoparticles mediated by gum ghatti (Anogeissus latifolia) and its biological activity  

PubMed Central

Background Gum ghatti is a proteinaceous edible, exudate tree gum of India and is also used in traditional medicine. A facile and ecofriendly green method has been developed for the synthesis of silver nanoparticles from silver nitrate using gum ghatti (Anogeissus latifolia) as a reducing and stabilizing agent. The influence of concentration of gum and reaction time on the synthesis of nanoparticles was studied. UV–visible spectroscopy, transmission electron microscopy and X-ray diffraction analytical techniques were used to characterize the synthesized nanoparticles. Results By optimizing the reaction conditions, we could achieve nearly monodispersed and size controlled spherical nanoparticles of around 5.7 ± 0.2 nm. A possible mechanism involved in the reduction and stabilization of nanoparticles has been investigated using Fourier transform infrared spectroscopy and Raman spectroscopy. Conclusions The synthesized silver nanoparticles had significant antibacterial action on both the Gram classes of bacteria. As the silver nanoparticles are encapsulated with functional group rich gum, they can be easily integrated for various biological applications. PMID:22571686

2012-01-01

291

Green synthesis of colloid silver nanoparticles and resulting biodegradable starch/silver nanocomposites.  

PubMed

Environmentally friendly silver nanocomposite films were prepared by an ex situ method consisting firstly in the preparation of colloidal silver dispersions and secondly in the dispersion of the as-prepared nanoparticles in a potato starch/glycerol matrix, keeping a green chemistry process all along the synthesis steps. In the first step concerned with the preparation of the colloidal silver dispersions, water, glucose and soluble starch were used as solvent, reducing agent and stabilizing agent, respectively. The influences of the glucose amount and reaction time were investigated on the size and size distribution of the silver nanoparticles. Two distinct silver nanoparticle populations in size (diameter around 5 nm size for the first one and from 20 to 50 nm for the second one) were distinguished and still highlighted in the potato starch/glycerol based nanocomposite films. It was remarkable that lower nanoparticle mean sizes were evidenced by both TEM and UV-vis analyses in the nanocomposites in comparison to the respective colloidal silver dispersions. A dispersion mechanism based on the potential interactions developed between the nanoparticles and the polymer matrix and on the polymer chain lengths was proposed to explain this morphology. These nanocomposite film series can be viewed as a promising candidate for many applications in antimicrobial packaging, biomedicines and sensors. PMID:24751276

Cheviron, Perrine; Gouanvé, Fabrice; Espuche, Eliane

2014-08-01

292

New Paradigm Shift for the Green Synthesis of Antibacterial Silver Nanoparticles Utilizing Plant Extracts  

PubMed Central

This review covers general information regarding the green synthesis of antibacterial silver nanoparticles. Owing to their antibacterial properties, silver nanoparticles are widely used in many areas, especially biomedical applications. In green synthesis practices, the chemical reducing agents are eliminated, and biological entities are utilized to convert silver ions to silver nanoparticles. Among the various biological entities, natural plant extracts have emerged as green reducing agents, providing eco-friendly routes for the preparation of silver nanomaterials. The most obvious merits of green synthesis are the increased biocompatibility of the resulting silver nanoparticles and the ease with which the reaction can be carried out. This review summarizes some of the plant extracts that are used to produce antibacterial silver nanoparticles. Additionally, background information regarding the green synthesis and antibacterial activity of silver nanoparticles is provided. Finally, the toxicological aspects of silver nanoparticles are briefly mentioned. PMID:25343010

2014-01-01

293

Enhanced silver nanoparticle synthesis by optimization of nitrate reductase activity.  

PubMed

Nanostructure materials are attracting a great deal of attention because of their potential for achieving specific processes and selectivity, especially in biological and pharmaceutical applications. The generation of silver nanoparticles using optimized nitrate reductase for the reduction of Ag(+) with the retention of enzymatic activity in the complex is being reported. This report involves the optimization of enzyme activity to bring about enhanced nanoparticle synthesis. Response surface methodology and central composite rotary design (CCRD) were employed to optimize a fermentation medium for the production of nitrate reductase by Bacillus licheniformis at pH 8. The four variables involved in the study of nitrate reductase were Glucose, Peptone, Yeast extract and KNO(3). Glucose had a significant effect on nitrate reductase production. The optimized medium containing (%) Glucose: 1.5, Peptone: 1, Yeast extract: 0.35 and KNO(3): 0.35 resulted in a nitrate reductase activity of 452.206 U/ml which is same as that of the central level. The medium A (showing least nitrate reductase activity) and the medium B (showing maximum nitrate reductase activity) were compared for the synthesis. Spectrophotometric analysis revealed that the particles exhibited a peak at 431 nm and the A(431) for the medium B was 2-fold greater than that of the medium A. The particles were also characterized using TEM. The particles synthesized using the optimized enzyme activity ranged from 10 to 80 nm and therefore can be extended to various medicinal applications. PMID:19796922

Vaidyanathan, Ramanathan; Gopalram, Shubaash; Kalishwaralal, Kalimuthu; Deepak, Venkataraman; Pandian, Sureshbabu Ram Kumar; Gurunathan, Sangiliyandi

2010-01-01

294

One-step green synthesis and characterization of leaf extract-mediated biocompatible silver and gold nanoparticles from Memecylon umbellatum  

PubMed Central

In this experiment, green-synthesized silver and gold nanoparticles were produced rapidly by treating silver and gold ions with an extract of Memecylon umbellatum leaf. The reaction process was simple and easy to handle, and was monitored using ultraviolet-visible spectroscopy. The effect of the phytochemicals present in M. umbellatum, including saponins, phenolic compounds, phytosterols, and quinones, on formation of stable silver and gold nanoparticles was investigated by Fourier-transform infrared spectroscopy. The morphology and crystalline phase of the nanoparticles were determined by transmission electron microscopy and energy-dispersive x-ray spectroscopy. The results indicate that the saponins, phytosterols, and phenolic compounds present in the plant extract play a major role in formation of silver and gold nanoparticles in their respective ions in solution. The characteristics of the nanoparticles formed suggest application of silver and gold nanoparticles as chemical sensors in the future. Given the simple and eco-friendly approach for synthesis, these nanoparticles could easily be commercialized for large-scale production. PMID:23569372

Arunachalam, Kantha D; Annamalai, Sathesh Kumar; Hari, Shanmugasundaram

2013-01-01

295

Immobilized silver nanoparticles enhance contact killing and show highest efficacy: elucidation of the mechanism of bactericidal action of silver  

NASA Astrophysics Data System (ADS)

Antimicrobial materials with immobilized/entrapped silver nanoparticles (AgNPs) are of considerable interest. There is significant debate on the mode of bactericidal action of AgNPs, and both contact killing and/or ion mediated killing have been proposed. In this study, AgNPs were immobilized on an amine-functionalized silica surface and their bactericidal activity was studied concurrently with the silver release profile over time. This was compared with similar studies performed using colloidal AgNPs and AgCl surfaces that released Ag ions. We conclude that contact killing is the predominant bactericidal mechanism and surface immobilized nanoparticles show greater efficacy than colloidal AgNPs, as well as a higher concentration of silver ions in solution. In addition, the AgNP immobilized substrate was used multiple times with good efficacy, indicating this immobilization protocol is effective for retaining AgNPs while maintaining their disinfection potential. The antibacterial surface was found to be extremely stable in aqueous medium and no significant leaching (~1.15% of total silver deposited) of the AgNPs was observed. Thus, immobilization of AgNPs on a surface may promote reuse, reduce environmental risks associated with leaching of AgNPs and enhance cost effectiveness.Antimicrobial materials with immobilized/entrapped silver nanoparticles (AgNPs) are of considerable interest. There is significant debate on the mode of bactericidal action of AgNPs, and both contact killing and/or ion mediated killing have been proposed. In this study, AgNPs were immobilized on an amine-functionalized silica surface and their bactericidal activity was studied concurrently with the silver release profile over time. This was compared with similar studies performed using colloidal AgNPs and AgCl surfaces that released Ag ions. We conclude that contact killing is the predominant bactericidal mechanism and surface immobilized nanoparticles show greater efficacy than colloidal AgNPs, as well as a higher concentration of silver ions in solution. In addition, the AgNP immobilized substrate was used multiple times with good efficacy, indicating this immobilization protocol is effective for retaining AgNPs while maintaining their disinfection potential. The antibacterial surface was found to be extremely stable in aqueous medium and no significant leaching (~1.15% of total silver deposited) of the AgNPs was observed. Thus, immobilization of AgNPs on a surface may promote reuse, reduce environmental risks associated with leaching of AgNPs and enhance cost effectiveness. Electronic supplementary information (ESI) available: Photographic image of silanization chamber; FEG-TEM image to show particle distribution of as-synthesized silver nanoparticles; photographic image of pristine amino-silanized glass and AgNPs immobilized glass; batch reactor fabrication for disinfection and silver release studies; surface coverage of silver nanoparticle immobilized glass substrate; and EDX analysis of the treated bacterial (E. coli) cells. See DOI: 10.1039/c3nr00024a

Agnihotri, Shekhar; Mukherji, Soumyo; Mukherji, Suparna

2013-07-01

296

Silver nanoparticles in hydrogels and microemulsions—a comparative account of their properties and bio-activity  

NASA Astrophysics Data System (ADS)

Stable silver nanoparticles were prepared in sodium Aerosol OT (AOT) based microemulsions and hydrogels. The various gel and microemulsion compositions used for nanoparticle synthesis were obtained from the phase diagram of the AOT/n-heptane/H2O system. It was found that only in gels can AOT play a dual role of stabilizer as well as reducing agent. In microemulsions, AOT acts as a stabilizer only. In gels, the commonly used NaBH4 reduction results in spherical silver nanoparticles while the AOT based reduction yields highly facetted particles. In microemulsion however, larger particles of undefined shapes are formed in low yield while for the gels, a large number of particles are formed. The synthesized silver nanoparticles show strong antibacterial activity.

Ray, Debajyoti; Chatterjee, Saptarshi; Sarkar, Keka; De, Swati

2014-09-01

297

Low temperature aqueous phase synthesis of silver/silver chloride plasmonic nanoparticles as visible light photocatalysts.  

PubMed

A one pot and environmentally benign synthetic route for plasmonic photocatalytic Ag@AgCl nanoparticles in a PVA-dissolved aqueous solution system is presented. The synthesized AgCl has a cubic-shape and its edge length can be controlled from ~57 to ~170 nm by varying the reaction temperature. In this system, PVA was used as a stabilizer for the formation of Ag@AgCl nanoparticles through interaction with Ag(+) ions. After partial reduction with l-arginine, the metallic Ag is formed on the surface of the AgCl substrates and the contents of the metallic Ag mainly affect both the visible-light absorption properties and the plasmonic photocatalytic efficiency of the Ag@AgCl nanocomposites. A plausible growth mechanism of metallic silver during the reduction process is proposed. More importantly, it is verified that the size of the AgCl substrate affected the light absorption region of the Ag@AgCl nanocomposite. PMID:23921540

Song, Jooyoung; Roh, Jongmin; Lee, Inkyu; Jang, Jyongsik

2013-10-14

298

Sesbania grandiflora leaf extract mediated green synthesis of antibacterial silver nanoparticles against selected human pathogens  

NASA Astrophysics Data System (ADS)

Simple, effective and rapid approach for the green synthesis of silver nanoparticles (AgNPs) using leaf extract of Sesbania grandiflora and their in vitro antibacterial activity against selected human pathogens has been demonstrated in the study. Various instrumental techniques were adopted to characterize the synthesized AgNPs viz. UV-Vis, FTIR, XRD, TEM, EDX and AFM. Surface Plasmon spectra for AgNPs are centered at 422 nm with dark brown color. The synthesized AgNPs were found to be spherical in shape with size in the range of 10-25 nm. The presence of water soluble proteins in the leaf extract was identified by FTIR which were found to be responsible for the reduction of silver ions (Ag+) to AgNPs. Moreover, the synthesized AgNPs showed potent antibacterial activity against multi-drug resistant (MDR) bacteria such as Salmonella enterica and Staphylococcus aureus.

Das, J.; Paul Das, M.; Velusamy, P.

2013-03-01

299

Sesbania grandiflora leaf extract mediated green synthesis of antibacterial silver nanoparticles against selected human pathogens.  

PubMed

Simple, effective and rapid approach for the green synthesis of silver nanoparticles (AgNPs) using leaf extract of Sesbania grandiflora and their in vitro antibacterial activity against selected human pathogens has been demonstrated in the study. Various instrumental techniques were adopted to characterize the synthesized AgNPs viz. UV-Vis, FTIR, XRD, TEM, EDX and AFM. Surface Plasmon spectra for AgNPs are centered at 422 nm with dark brown color. The synthesized AgNPs were found to be spherical in shape with size in the range of 10-25 nm. The presence of water soluble proteins in the leaf extract was identified by FTIR which were found to be responsible for the reduction of silver ions (Ag(+)) to AgNPs. Moreover, the synthesized AgNPs showed potent antibacterial activity against multi-drug resistant (MDR) bacteria such as Salmonella enterica and Staphylococcus aureus. PMID:23270884

Das, J; Paul Das, M; Velusamy, P

2013-03-01

300

Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol  

NASA Astrophysics Data System (ADS)

The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (1 1 1), (2 0 0), (2 2 2) and (3 1 1) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs.

Naraginti, Saraschandra; Sivakumar, A.

2014-07-01

301

Eco-friendly synthesis of silver and gold nanoparticles with enhanced bactericidal activity and study of silver catalyzed reduction of 4-nitrophenol.  

PubMed

The present study reports a simple and robust method for synthesis of silver and gold nanoparticles using Coleus forskohlii root extract as reducing and stabilizing agent. Stable silver nanoparticles (AgNPs) and gold nanopoarticles (AuNPs) were formed on treatment of an aqueous silver nitrate (AgNO3) and chloroauric acid (HAuCl4) solutions with the root extract. The nanoparticles obtained were characterized by UV-Visible spectroscopy, Transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FT-IR). UV-Vis and TEM analysis indicate that with higher quantities of root extract, the interaction is enhanced leading to size reduction of spherical metal nanoparticles. XRD confirms face-centered cubic phase and the diffraction peaks can be attributed to (111), (200), (222) and (311) planes for these nanoparticles. These synthesized Ag and Au nanoparticles were found to exhibit excellent bactericidal activity against clinically isolated selected pathogens such as Escherichia coli (E. coli), Pseudomonas aeruginosa (P. aeruginosa) and Staphylococcus aureus (S. aureus). The synthesized AgNPs were also found to function as an efficient green catalyst in the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) by sodium borohydride, which was apparent from the periodical color change from bright yellow to colorless, after the addition of AgNPs. PMID:24681320

Naraginti, Saraschandra; Sivakumar, A

2014-07-15

302

Nanoparticle Silver Catalysts That Show Enhanced Activity for Carbon Dioxide Electrolysis  

E-print Network

Nanoparticle Silver Catalysts That Show Enhanced Activity for Carbon Dioxide Electrolysis Amin is about 10 times higher on 5 nm silver nanoparticles than on bulk silver even though measurements of two catalysts, a silver metal and ionic liquid 1- ethyl-3-methylimidazolium tetrafluoroborate (EMIM

Kenis, Paul J. A.

303

Green synthesis, antimicrobial and cytotoxic effects of silver nanoparticles using Eucalyptus chapmaniana leaves extract  

PubMed Central

Objective To synthesize silver nanopaticles from leaves extract of Eucalyptus chapmaniana (E. chapmaniana) and test the antimicrobial of the nanoparticles against different pathogenic bacteria, yeast and its toxicity against human acute promyelocytic leukemia (HL-60) cell line. Methods Ten milliliter of leaves extract was mixed with 90 mL of 0.01 mmol/mL or 0.02 mmol/mL aqueous AgNO3 and exposed to sun light for 1 h. A change from yellowish to reddish brown color was observed. Characterization using UV-vis spectrophotometery and X-ray diffraction analysis were performed. Antimicrobial activity against six microorganisms was tested using well diffusion method and cytoxicity test using 3-(4, 5-Dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide, a yellow tetrazole was obtained on the human leukemia cell line (HL-60). Results UV-vis spectral analysis showed silver surface plasmon resonance band at 413 nm. X-ray diffraction showed that the particles were crystalline in nature with face centered cubic structure of the bulk silver with broad beaks at 38.50° and 44.76°. The synthesized silver nanoparticles efficiently inhibited various pathogenic organisms and reduced viability of the HL-60 cells in a dose-dependent manner. Conclusions It has been demonstrated that the extract of E. chapmaniana leaves are capable of producing silver nanoparticles extracellularly and the Ag nanoparticles are quite stable in solution. Further studies are needed to fully characterize the toxicity and the mechanisms involved with the antimicrobial and anticancer activity of these particles. PMID:23570018

Sulaiman, Ghassan Mohammad; Mohammed, Wasnaa Hatif; Marzoog, Thorria Radam; Al-Amiery, Ahmed Abdul Amir; Kadhum, Abdul Amir H.; Mohamad, Abu Bakar

2013-01-01

304

Catalytic degradation of organic dyes using biosynthesized silver nanoparticles.  

PubMed

The green synthesis of metallic nanoparticles paved the way to improve and protect the environment by decreasing the use of toxic chemicals and eliminating biological risks in biomedical applications. Plant mediated synthesis of metal nanoparticles is gaining more importance owing to its simplicity, rapid rate of synthesis of nanoparticles and eco-friendliness. The present article reports an environmentally benign and unexploited method for the synthesis of silver nanocatalysts using Trigonella foenum-graecum seeds, which is a potential source of phytochemicals. The UV-visible absorption spectra of the silver samples exhibited distinct band centered around 400-440 nm. The major phytochemicals present in the seed extract responsible for the formation of silver nanocatalysts are identified using FTIR spectroscopy. The report emphasizes the effect of the size of silver nanoparticles on the degradation rate of hazardous dyes, methyl orange, methylene blue and eosin Y by NaBH4. The efficiency of silver nanoparticles as a promising candidate for the catalysis of organic dyes by NaBH4 through the electron transfer process is established in the present study. PMID:24210247

Vidhu, V K; Philip, Daizy

2014-01-01

305

Hydroxy propyl cellulose capped silver nanoparticles produced by simple dialysis process  

SciTech Connect

Silver (Ag) nanoparticles ({approx}6 nm) were synthesized using a novel dialysis process. Silver nitrate was used as a starting precursor, ethylene glycol as solvent and hydroxy propyl cellulose (HPC) introduced as a capping agent. Different batches of reaction mixtures were prepared with different concentrations of silver nitrate (AgNO{sub 3}). After the reduction and aging, these solutions were subjected to ultra-violet visible spectroscopy (UVS). Optimized solution, containing 250 mg AgNO{sub 3} revealed strong plasmon resonance peak at {approx}410 nm in the spectrum indicating good colloidal state of Ag nanoparticles in the diluted solution. The optimized solution was subjected to dialysis process to remove any unreacted solvent. UVS of the optimized solution after dialysis showed the plasmon resonance peak shifting to {approx}440 nm indicating the reduction of Ag ions into zero-valent Ag. This solution was dried at 80 {sup o}C and the resultant HPC capped Ag (HPC/Ag) nanoparticles were studied using transmission electron microscopy (TEM) for their particle size and morphology. The particle size distribution (PSD) analysis of these nanoparticles showed skewed distribution plot with particle size ranging from 3 to 18 nm. The nanoparticles were characterized for phase composition using X-ray diffractrometry (XRD) and Fourier transform infrared spectroscopy (FT-IR).

Francis, L. [University of Genova, Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, 16146 Genova (Italy)] [University of Genova, Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, 16146 Genova (Italy); Balakrishnan, A. [Laboratoire SIMaP - GPM2, Grenoble-INP/UJF/CNRS BP46, 38042 Saint Martin d'Heres cedex (France)] [Laboratoire SIMaP - GPM2, Grenoble-INP/UJF/CNRS BP46, 38042 Saint Martin d'Heres cedex (France); Sanosh, K.P. [Department of Innovation Engineering, University of Lecce, via per Monteroni, 73100 Lecce (Italy)] [Department of Innovation Engineering, University of Lecce, via per Monteroni, 73100 Lecce (Italy); Marsano, E., E-mail: marsano@chimica.unige.it [University of Genova, Department of Chemistry and Industrial Chemistry, via Dodecaneso 31, 16146 Genova (Italy)

2010-08-15

306

Formation of Silver Nanoparticles and Self-Assembled Two-Dimensional Ordered Superlattice  

E-print Network

of the silver nanoparticle colloidal phase obtained finally show that the system is monodisperse and can remainFormation of Silver Nanoparticles and Self-Assembled Two-Dimensional Ordered Superlattice Shengtai, 2000 1-Nonanethiol-capped silver nanoparticles of about 4.18 nm in diameter were prepared using

Gao, Hongjun

307

Silver, Gold, Palladium Nanoparticles: Ligand Design, Synthesis and Polymer Composites  

NASA Astrophysics Data System (ADS)

Metal nanoparticles, especially gold nanoparticles (AuNPs), have been extensively studied due to their interesting optical properties and potential applications in emerging technologies like drug delivery, cancer therapy, catalysis, chemical and bio-sensing and microelectronics devices. Alkyl thiol ligands in the form of self assembled monolayers are often used to stabilize and functionalize the gold nanoparticles while other types of ligands have been rarely employed and the properties of AuNPs protected by different types of ligands have not been studied comprehensively and comparatively. This dissertation reports the first comparative studies on the thermal and chemical stability of AuNPs protected by alkyl thiolates, alkyl selenolates, dialkyl dithiophosphinates, and dialkyl dithiophosphates (Chapters 2 and 3). AuNPs protected by dialkyl dithiophosphinates and dialkyl dithiophosphates are unprecedented. All AuNPs were prepared from amine protected precursor AuNPs by ligand exchange to ensure similar size, size distribution, and chemical composition. They were extensively characterized by solution 1H-NMR and UV-VIS spectroscopy, transmission electron microscopy (TEM), thermal analysis, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) analysis. For the first time, thermal stability was investigated by differential scanning calorimetry (DSC) that provided more accurate decomposition temperatures and enthalpies, whereas chemical stability was tested as the availability of the gold surface towards etching with cyanide in different solvents. Surprisingly, alkyl selenolate protected AuNPs are thermally less stable than alkyl thiolate protected AuNPs despite their proposed stronger binding to the gold surface and a much more crystalline monolayer, which suggests that different decomposition mechanisms apply to alkyl thiolate and alkyl selenolate protected AuNPs. Dialkyl dithiophosphinates and dialkyl dithiophosphates protected AuNPs are thermally least stable, although dialkyl dithiophosphates bind as bi-dentate ligands and are most stable towards cyanide etching. In contrast, dialkyl dithiophosphinates show mixed mono- and bi-dentate binding that generates loosely packed monolayers of low degree of crystallinity. Another part of this thesis (Chapter 4 and 5) employs AuNPs and silver particles as fillers to improve the electrical and thermal conductivities of polyurethane composites. High anisotropic electrical conductivity of thin composite films are obtained after curing at unprecedentedly low gold contents, which is reasoned with the coagulation of AuNPs to conductive gold networks in domains of high concentration of AuNPs. Silver particles and flakes of sizes between 20 nm and 1.5 micron were dispersed in polyurethane to investigate the effect of their size, morphology, aggregation, and dispersion on the thermal conductivity of the composites. Unexpectedly, composites filled with micron sized silver particles outperformed those filled with silver nanoparticles in thermal conductivity and stability. Finally, PdNPs were synthesized in the presence of thiolate ligands of different conical bulk (single phase surfactant free approach) to study the influence of the different ligands on their size (Chapter 6). No systematic effect was observed in contrast to a similar study on AuNPs, which is reasoned with a weaker binding of ligands to the Pd surface.

Iqbal, Muhammad

308

A Biological Approach to the Synthesis of Silver Nanoparticles with Streptomyces sp JAR1 and its Antimicrobial Activity  

PubMed Central

The biological approach to synthesize metal nanoparticles is an important aspect of current nanotechnology research. Silver nanoparticles have been well-known for their inhibitory and antimicrobial effects. The ever-increasing antibiotic resistance in pathogenic and opportunistic microorganisms is a major threat to the health care industry. In the present investigation, silver nanoparticles have been successfully biosynthesized by Streptomyces sp JAR1. Biosynthesized silver nanoparticles were characterized by means of several analytical techniques including a UV-Visible spectrophotometer, Fourier transform infrared spectroscopy, X-ray diffraction pattern analysis, and atomic force microscopy. An evaluation of the antimicrobial activity of silver nanoparticles (AgNPs) was carried out against clinically important pathogenic microorganisms. The metal nanoparticles were also evaluated for their combined effects with antibiotics against the clinical pathogens. The antibacterial activities of the antibiotics increased in the presence of the biologically synthesized AgNPs against the clinically important pathogens. The highest enhancing effect was observed for erythromycin against the test pathogens. PMID:23833724

Chauhan, Ritika; Kumar, Abhishek; Abraham, Jayanthi

2013-01-01

309

The effect of the deposition parameters on size, distribution and antimicrobial properties of photoinduced silver nanoparticles on titania coatings  

NASA Astrophysics Data System (ADS)

Controlled photodeposition of silver nanoparticles (AgNP) on titania coatings using two different sources of UV light is described. Titania (anatase) thin films were prepared by the sol-gel dip-coating method on silicon wafers. AgNPs were grown on the titania surface as a result of UV illumination of titania films immersed in aqueous solutions of silver nitrate. UV xenon lamp or excimer laser, both operating at the wavelength 351 ± 5 nm, was used as illumination sources. The AFM topography of AgNP/TiO 2 nanocomposites revealed that silver nanoparticles could be synthesized by both sources of illumination, however the photocatalysis carried out by UV light from xenon lamp illumination leads to larger AgNP than those synthesized using the laser beam. It was found that the increasing concentration of silver ions in the initial solution increases the number of Ag nanoparticles on the titania surface, while longer time of irradiation results the growth of larger size nanoparticles. Antibacterial tests performed on TiO 2 covered by Ag nanoparticles revealed that increasing density of nanoparticles enhances the inhibition of bacterial growth. It was also found that antibacterial activity drops by only 10-15% after 6 cycles compared to the initial use.

Piwo?ski, Ireneusz; K?dzio?a, Kinga; Kisielewska, Aneta; Soliwoda, Katarzyna; Wolszczak, Marian; Lisowska, Katarzyna; Wro?ska, Natalia; Felczak, Aleksandra

2011-06-01

310

Green biosynthesis of silver nanoparticles using Curcuma longa tuber powder  

PubMed Central

Green synthesis of noble metal nanoparticles is a vastly developing area of research. Metallic nanoparticles have received great attention from chemists, physicists, biologists, and engineers who wish to use them for the development of a new-generation of nanodevices. In this study, silver nanoparticles were biosynthesized from aqueous silver nitrate through a simple and eco-friendly route using Curcuma longa tuber-powder extracts, which acted as a reductant and stabilizer simultaneously. Characterizations of nanoparticles were done using different methods, which included ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy-dispersive X-ray fluorescence spectrometry, and Fourier-transform infrared spectroscopy. The ultraviolet-visible spectrum of the aqueous medium containing silver nanoparticles showed an absorption peak at around 415 nm. Transmission electron microscopy showed that mean diameter and standard deviation for the formation of silver nanoparticles was 6.30 ± 2.64 nm. Powder X-ray diffraction showed that the particles are crystalline in nature, with a face-centered cubic structure. The most needed outcome of this work will be the development of value-added products from C. longa for biomedical and nanotechnology-based industries. PMID:23341739

Shameli, Kamyar; Ahmad, Mansor Bin; Zamanian, Ali; Sangpour, Parvanh; Shabanzadeh, Parvaneh; Abdollahi, Yadollah; Zargar, Mohsen

2012-01-01

311

Cellular oxido-reductive proteins of Chlamydomonas reinhardtii control the biosynthesis of silver nanoparticles  

PubMed Central

Background Elucidation of molecular mechanism of silver nanoparticles (SNPs) biosynthesis is important to control its size, shape and monodispersity. The evaluation of molecular mechanism of biosynthesis of SNPs is of prime importance for the commercialization and methodology development for controlling the shape and size (uniform distribution) of SNPs. The unicellular algae Chlamydomonas reinhardtii was exploited as a model system to elucidate the role of cellular proteins in SNPs biosynthesis. Results The C. reinhardtii cell free extract (in vitro) and in vivo cells mediated synthesis of silver nanoparticles reveals SNPs of size range 5 ± 1 to 15 ± 2 nm and 5 ± 1 to 35 ± 5 nm respectively. In vivo biosynthesized SNPs were localized in the peripheral cytoplasm and at one side of flagella root, the site of pathway of ATP transport and its synthesis related enzymes. This provides an evidence for the involvement of oxidoreductive proteins in biosynthesis and stabilization of SNPs. Alteration in size distribution and decrease of synthesis rate of SNPs in protein-depleted fractions confirmed the involvement of cellular proteins in SNPs biosynthesis. Spectroscopic and SDS-PAGE analysis indicate the association of various proteins on C. reinhardtii mediated in vivo and in vitro biosynthesized SNPs. We have identified various cellular proteins associated with biosynthesized (in vivo and in vitro) SNPs by using MALDI-MS-MS, like ATP synthase, superoxide dismutase, carbonic anhydrase, ferredoxin-NADP+ reductase, histone etc. However, these proteins were not associated on the incubation of pre-synthesized silver nanoparticles in vitro. Conclusion Present study provides the indication of involvement of molecular machinery and various cellular proteins in the biosynthesis of silver nanoparticles. In this report, the study is mainly focused towards understanding the role of diverse cellular protein in the synthesis and capping of silver nanoparticles using C. reinhardtii as a model system. PMID:22152042

2011-01-01

312

Preparation of starch-stabilized silver nanoparticles from amylose-sodium palmitate inclusion complexes  

Technology Transfer Automated Retrieval System (TEKTRAN)

Starch-stabilized silver nanoparticles were prepared from amylose-sodium palmitate complexes by first converting sodium palmitate to silver palmitate by reaction with silver nitrate and then reducing the silver ion to metallic silver. This process produced water solutions that could be dried and the...

313

Sulfidation of Silver Nanoparticles: Natural antidote to their toxicity  

PubMed Central

Nanomaterials are highly dynamic in biological and environmental media. A critical need for advancing environmental health and safety research for nanomaterials is to identify commonly occurring physical and chemical transformations affecting nanomaterial properties and toxicity. Silver nanoparticles, one of the most ecotoxic and well-studied nanomaterials, readily sulfidize in the environment. Here, we show that very low degrees of sulfidation (0.019 S/Ag mass ratio) universally and significantly decreases the toxicity of silver nanoparticles to four diverse types of aquatic and terrestrial eukaryotic organisms. Toxicity reduction is primarily associated with a decrease in Ag+ availability after sulfidation due to the lower solubility of Ag2S relative to elemental Ag (Ag(0)). We also show that chloride in exposure media determines silver nanoparticle toxicity by controlling the speciation of Ag. These results highlight the need to consider environmental transformation of NPs in assessing their toxicity to accurately portray their potential environmental risks. PMID:24180218

Levard, Clément; Hotze, Ernest M.; Colman, Benjamin P.; Truong, Lisa; Yang, X. Y.; Bone, Audrey; Brown, Gordon E.; Tanguay, Robert L.; Di Giulio, Richard T.; Bernhardt, Emily S.; Meyer, Joel N.; Wiesner, Mark R.; Lowry, Gregory V.

2014-01-01

314

Silver Nanoparticle Fabrication by Laser Ablation in Polyvinyl Alcohol Solutions  

NASA Astrophysics Data System (ADS)

A laser ablation technique is applied for synthesis of silver nanoparticles in different concentrations of polyvinyl alcohol (PVA) aqueous solution. The ablation of high pure silver plate in the solution is carried out by a nanosecond Q-switched Nd:YAG pulsed laser. X-ray diffraction and transmission electron microscopy are implemented to explore the particles sizes. The effects of PVA concentrations on the absorbance of the silver nanoparticles are studied as well, by using a UV-vis spectrophotometer. The preparation process is carried out for deionized water as a reference sample. The comparison of the obtained results with the reference sample shows that the formation efficiency of nanoparticles in PVA is much higher and the sizes of particles are also smaller.

Halimah Mohamed., K.; Mahmoud Goodarz, Naseri; Amir, Reza Sadrolhosseini; Arash, Dehzangi; Ahmad, Kamalianfar; Elias, B. Saion; Reza, Zamiri; Hossein Abastabar, Ahangar; Burhanuddin, Y. Majlis

2014-07-01

315

Evolution of Silver Nanoparticles in the Rat Lung Investigated by X-ray Absorption Spectroscopy.  

PubMed

Following a 6-h inhalation exposure to aerosolized 20 and 110 nm diameter silver nanoparticles, lung tissues from rats were investigated with X-ray absorption spectroscopy, which can identify the chemical state of silver species. Lung tissues were processed immediately after sacrifice of the animals at 0, 1, 3, and 7 days post exposure and the samples were stored in an inert and low-temperature environment until measured. We found that it is critical to follow a proper processing, storage and measurement protocol; otherwise only silver oxides are detected after inhalation even for the larger nanoparticles. The results of X-ray absorption spectroscopy measurements taken in air at 85 K suggest that the dominating silver species in all the postexposure lung tissues were metallic silver, not silver oxide, or solvated silver cations. The results further indicate that the silver nanoparticles in the tissues were transformed from the original nanoparticles to other forms of metallic silver nanomaterials and the rate of this transformation depended on the size of the original nanoparticles. We found that 20 nm diameter silver nanoparticles were significantly modified after aerosolization and 6-h inhalation/deposition, whereas larger, 110 nm diameter nanoparticles were largely unchanged. Over the seven-day postexposure period the smaller 20 nm silver nanoparticles underwent less change in the lung tissue than the larger 110 nm silver nanoparticles. In contrast, silica-coated gold nanoparticles did not undergo any modification processes and remained as the initial nanoparticles throughout the 7-day study period. PMID:25517690

Davidson, R Andrew; Anderson, Donald S; Van Winkle, Laura S; Pinkerton, Kent E; Guo, T

2015-01-15

316

Biogenic synthesis of multi-applicative silver nanoparticles by using Ziziphus Jujuba leaf extract.  

PubMed

Herein, we are reporting for the first time one step biogenic synthesis of silver nanoparticles (AgNPs) at room temperature by using Ziziphus Jujuba leaf extract as a reducing and stabilizing agent. The process of nanoparticles preparation is green, rapid, environmentally benign and cost effective. The synthesized AgNPs were characterized by means of UV-Vis., XRD, FT-IR, TEM, DLS and Zeta potential. The absorption band centered at ?max 434 nm in UV-Vis. reflects surface plasmon resonance (SPR) of AgNPs. XRD analysis revealed, that biosynthesized AgNPs are crystalline in nature with the face centered cubic structure. FT-IR analysis indicates that nanoparticles were capped with the leaf extract. TEM images shows the synthesized nanoparticles are having different shapes with 20-30 nm size. The data obtained from DLS that support the hydrodynamic size of 28 nm. Zeta potential of -26.4 mV indicates that the nanoparticles were highly stable in colloidal state. The effect of pH, quantity of leaf extract and concentrations of AgNO3 were also studied to attend control over the particle size and stability. The synthesized AgNPs shows highly efficient catalytic activity towards the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) and Methylene Blue (MB) for environmental protection. Synthesized AgNPs also exhibited good antimicrobial activity against Escherichia coli. PMID:25459621

Gavade, N L; Kadam, A N; Suwarnkar, M B; Ghodake, V P; Garadkar, K M

2015-02-01

317

Biogenic synthesis of multi-applicative silver nanoparticles by using Ziziphus Jujuba leaf extract  

NASA Astrophysics Data System (ADS)

Herein, we are reporting for the first time one step biogenic synthesis of silver nanoparticles (AgNPs) at room temperature by using Ziziphus Jujuba leaf extract as a reducing and stabilizing agent. The process of nanoparticles preparation is green, rapid, environmentally benign and cost effective. The synthesized AgNPs were characterized by means of UV-Vis., XRD, FT-IR, TEM, DLS and Zeta potential. The absorption band centered at ?max 434 nm in UV-Vis. reflects surface plasmon resonance (SPR) of AgNPs. XRD analysis revealed, that biosynthesized AgNPs are crystalline in nature with the face centered cubic structure. FT-IR analysis indicates that nanoparticles were capped with the leaf extract. TEM images shows the synthesized nanoparticles are having different shapes with 20-30 nm size. The data obtained from DLS that support the hydrodynamic size of 28 nm. Zeta potential of -26.4 mV indicates that the nanoparticles were highly stable in colloidal state. The effect of pH, quantity of leaf extract and concentrations of AgNO3 were also studied to attend control over the particle size and stability. The synthesized AgNPs shows highly efficient catalytic activity towards the reduction of anthropogenic pollutant 4-nitrophenol (4-NP) and Methylene Blue (MB) for environmental protection. Synthesized AgNPs also exhibited good antimicrobial activity against Escherichia coli.

Gavade, N. L.; Kadam, A. N.; Suwarnkar, M. B.; Ghodake, V. P.; Garadkar, K. M.

2015-02-01

318

Biosynthesis of silver and gold nanoparticles using Bacillus licheniformis.  

PubMed

Owing to the wide-ranging applications of noble metal nanoparticles in diverse areas of science and technology, different methods have been proposed for their synthesis. Here, we describe the methods for the intracellular biosynthesis of silver and gold nanoparticles using the bacterium Bacillus licheniformis KK2 and this same procedure can be followed for other bacteria as well. The biological synthesis of nanoparticles is highly eco-friendly and possesses distinct advantages such as enhanced stability, better control over the size, shape, and monodispersity of the nanoparticles, when compared with the more traditional physical and chemical methods which often involves the use of hazardous chemicals creating environmental concern. PMID:22791422

Sriram, Muthu Irulappan; Kalishwaralal, Kalimuthu; Gurunathan, Sangiliyandi

2012-01-01

319

In situ formation of silver nanoparticles in PMMA via reduction of silver ions by butylated hydroxytoluene  

Microsoft Academic Search

Silver nanoparticles (Ag NPs) were efficiently generated by in situ reduction of silver ions via butylated hydroxytoluene\\u000a (BHT), in poly(methyl methacrylate). The characterization of Ag\\/PMMA by TEM, SEM, XRD, and FTIR indicated that Ag NPs with\\u000a a face center cubic (fcc) crystal structure and a mean diameter of about 30 nm were dispersed in PMMA matrix with a relatively\\u000a uniform distribution.

M. Z. Kassaee; M. Mohammadkhani; A. Akhavan; R. Mohammadi

2011-01-01

320

Interaction between Silver Nanoparticles and Spinach Leaf  

NASA Astrophysics Data System (ADS)

Interactions of engineered nanoparticles (ENPs) with plant surfaces are critical to assessing the bioavailability of ENPs to edible plants and to further evaluating impacts of ENPs on ecological health and food safety. Silver nanoparticles (i.e., nanoAg) could enter the agroecosystems either as an active ingredient in pesticides or from other industrial and consumer applications. Thus, in the events of pesticide application, rainfall, and irrigation, vegetable leaves could become in contact and then interact with nanoAg. The present study was to assess whether the interaction of nanoAg with spinach leaves can be described by classical sorption models and to what extent it depends on and varies with dispersion methods, environmental temperature, and ion release. We investigated the stability and ion release of nanoAg dispersed by sodium dodecyl sulfate (SDS, 1%) and humic acid (HA, 10 mg C/L) solutions, as well as sorption and desorption of nanoAg on and from the fresh spinach leaf. Results showed SDS-nanoAg released about 2%-8% more Ag ion than HA-nanoAg. The sorption of Ag ion, described by the Freundlich model in the initial concentration range of 0.6-50 mg/L, was 2-4 times higher than that of nanoAg. The sorption of nanoAg on spinach leaf can be fitted by the Langmuir model, and the maximum sorption amount of HA-nanoAg and SDS-nanoAg was 0.21 and 0.41 mg/g, respectively. The higher sorption of SDS-nanoAg relative to that of HA-nanoAg could be partially resulted from the higher release of Ag ion from the former. The maximum desorption amount of HA-nanoAg and SDS-nanoAg in 1% SDS solution was 0.08 and 0.10 mg/g, respectively. NanoAg attachment on and its penetration to the spinach leaf was visualized by the Scanning Electron Microscope equipped with an Energy Dispersive Spectrometer (SEM-EDS). It is equally important that the less sorption of nanoAg under low environmental temperature could be partially due to the closure of stomata, as verified by SEM-EDS. CytoViva Hyperspectral Imaging System was also employed to map the distribution of nanoAg in the leaf profile. Significant sorption of nanoAg on spinach leaf should urge the precaution with potential widespread use of ENPs in agriculture.

Tian, Y.; Li, H.; Zhang, Y.; Riser, E.; He, S.; Zhang, W.

2013-12-01

321

Ultrasensitive nanosensor based on silver nanoparticles to detect hydrogen peroxide  

NASA Astrophysics Data System (ADS)

Studies to determine the concentration of hydrogen peroxide (H2O2) are important in biological system due to cellular damages provoked by reative oxygen species that include H2O2. An alternative to detect H2O2 is through an optical nanosensors based on silver nanoparticles, which have great potential for chemical and biological sensing applications. Here we demonstrate that attenuated total reflectance (ATR) from interaction of silver nanoparticles and hydrogen peroxide were able to detect very low levels of H2O2 around 0,001mM.

Oliveira, J. P.; Prado, A. R.; Volkers, R. E.; Pontes, M. J.; Ribeiro, M. N.; Nogueira, B. V.; Guimãraes, M. C. C.

2014-08-01

322

Silver Nanoparticles as Real Topical Bullets for Wound Healing  

PubMed Central

Nanotechnology is on the threshold of providing a host of new materials and approaches, revolutionizing the medical and pharmaceutical fields. Several areas of medical care are already profiting from the advantage that nanotechnology offers. Recently, silver nanoparticles are attracting interest for a clinical application because of its potential biological properties such as antibacterial activity, anti-inflammatory effects, and wound healing efficacy, which could be exploited in developing better dressings for wounds and ulcers. This article reviews the role of silver nanoparticles in wound healing. PMID:24527370

Gunasekaran, Thirumurugan; Nigusse, Tadele; Dhanaraju, Magharla Dasaratha

2012-01-01

323

Laser-fabricated castor oil-capped silver nanoparticles  

PubMed Central

Silver nanoparticles were fabricated by ablation of a pure silver plate immersed in castor oil. A Nd:YAG-pulsed Q-switch laser with 1064-nm wavelength and 10-Hz frequency was used to ablate the plate for 10 minutes. The sample was characterized by ultraviolet-visible, atomic absorption, Fourier transform-infrared spectroscopies, and transmission electron microscopy. The results of the fabricated sample showed that the nanoparticles in castor oil were about 5-nm in diameter, well dispersed, and showed stability for a long period of time. PMID:21698083

Zamiri, Reza; Zakaria, Azmi; Abbastabar, Hossein; Darroudi, Majid; Husin, Mohd Shahril; Mahdi, Mohd Adzir

2011-01-01

324

Nonlinear optical characterization of silver nanoparticles embedded in phosphate glass  

NASA Astrophysics Data System (ADS)

The nonequilibrium carrier dynamics in spherical silver nanoparticles embedded in aluminophosphate glass system was explored by femtosecond optical pump-probe technique. Photoluminescence and absorption spectroscopy were used for characterization of linear optical properties and particle size estimation. The two temperature model is employed to study the hot electron subsystem and evolution of electronic and lattice temperatures. The electron scattering dynamics on the 10 -13-10 -12 sec scale and two-photon absorption process are discussed. The laser-induced coherent vibrations of silver nanoparticles were observed in transient transmission experiments for relatively large particles with radii ~35 nm.

Lysenko, S.; Jimenez, J.; Zhang, G.; Liu, H.

2006-03-01

325

An insight into silver nanoparticles bioavailability in rats.  

PubMed

A comprehensive study of the bioavailability of orally administered silver nanoparticles (AgNPs) was carried out using a rat model. The silver uptake was monitored in liver and kidney tissues, as well as in urine and in feces. Significant accumulation of silver was found in both organs, the liver being the principal target of AgNPs. A significant (?50%) fraction of silver was found in feces whereas the fraction excreted via urine was negligible (<0.01%). Intact silver nanoparticles were found in feces by asymmetric flow field-flow fractionation (AsFlFFF) coupled with UV-Vis analysis. Laser ablation-ICP MS imaging showed that AgNPs were able to penetrate into the liver, in contrast to kidneys where they were retained in the cortex. Silver speciation analysis in cytosols from kidneys showed the metallothionein complex as the major species whereas in the liver the majority of silver was bound to high-molecular (70-25 kDa) proteins. These findings demonstrate the presence of Ag(i), released by the oxidation of AgNPs in the biological environment. PMID:25363792

Jiménez-Lamana, Javier; Laborda, Francisco; Bolea, Eduardo; Abad-Álvaro, Isabel; Castillo, Juan R; Bianga, Juliusz; He, Man; Bierla, Katarzyna; Mounicou, Sandra; Ouerdane, Laurent; Gaillet, Sylvie; Rouanet, Jean-Max; Szpunar, Joanna

2014-12-20

326

Size-Controlled Dissolution of Organic-Coated Silver Nanoparticles  

SciTech Connect

The solubility of Ag NPs can affect their toxicity and persistence in the environment. We measured the solubility of organic-coated silver nanoparticles (Ag NPs) having particle diameters ranging from 5 to 80 nm that were synthesized using various methods, and with different organic polymer coatings including poly(vinylpyrrolidone) and gum arabic. The size and morphology of Ag NPs were characterized by transmission electron microscopy (TEM). X-ray absorption fine structure (XAFS) spectroscopy and synchrotron-based total X-ray scattering and pair distribution function (PDF) analysis were used to determine the local structure around Ag and evaluate changes in crystal lattice parameters and structure as a function of NP size. Ag NP solubility dispersed in 1 mM NaHCO{sub 3} at pH 8 was found to be well correlated with particle size based on the distribution of measured TEM sizes as predicted by the modified Kelvin equation. Solubility of Ag NPs was not affected by the synthesis method and coating as much as by their size. Based on the modified Kelvin equation, the surface tension of Ag NPs was found to be {approx}1 J/m{sup 2}, which is expected for bulk fcc (face centered cubic) silver. Analysis of XAFS, X-ray scattering, and PDFs confirm that the lattice parameter, {alpha}, of the fcc crystal structure of Ag NPs did not change with particle size for Ag NPs as small as 6 nm, indicating the absence of lattice strain. These results are consistent with the finding that Ag NP solubility can be estimated based on TEM-derived particle size using the modified Kelvin equation for particles in the size range of 5-40 nm in diameter.

Ma, Rui; Levard, Clément; Marinakos, Stella M.; Cheng, Yingwen; Liu, Jie; Michel, F. Marc; Brown, Jr., Gordon E.; Lowry, Gregory V. (Duke)

2012-04-02

327

Characterization of silver nanoparticles deposited by an enzyme  

NASA Astrophysics Data System (ADS)

Based on their various interesting properties metal nanoparticles show the potential as analytical tool in electronic, optical, and catalytical applications. The different properties depending on composition, shape, and size of the single particles were utilized in many different approaches such as optics, magnetics and laser technology1. We present a way for enzymatic deposition of silver nanoparticles and a bioanalytical application in DNA microarray technology for this method. The technology consists of a microstructured chip with 10?m broad electrode gaps on the surface and specially designed readout device2. In principle we immobilize gold nanoparticle-labelled DNA in a gap between two electrodes. Afterwards a silver deposition on the bound gold nanoparticles generates a conductive layer between the electrodes. The measured drop in the resistance serves as signal for the chip-based electrical detection of DNA 3. To further optimize this system the gold nanoparticles as seed are replaced by the enzyme horseradish peroxidase. For a better understanding of the enzymatically silver deposition process the formed silver particles were analyzed by spectroscopic characterization on a single particle level. Further investigations of these particles by AFM and SEM should give a hint to the connection between size/shape and the plasmonic properties at individual particles.

Schüler, Thomas; Möller, Robert; Steinbrück, Andrea; Fritzsche, Wolfgang; Popp, Jürgen

2007-07-01

328

Facile preparation of silver nanoparticle films as an efficient surface-enhanced Raman scattering substrate  

NASA Astrophysics Data System (ADS)

Here, we report a new and facile method to prepare silver nanoparticles (Ag NPs) film for surface-enhanced Raman scattering (SERS)-based sensing. The porous Ni foam was used as a template to generate high quality of Ag NPs by seed-mediated growth of metallic nanoparticles. The preparation process is very economic and environment-friendly, can achieve the recovery of the raw materials. We found that the type of silver-plating solution and the growth time are two key factors to determine the magnitude of SERS signal enhancement. Using rhodamine 6G (R6G) and 4-animothiophenol (4-ATP) as probe molecules, the created Ag NP films exhibited relatively high enhancement ability, good stability, and well reproducibility. The synthesized SERS-active substrate was further used to detect melamine molecules, an illegal additive in infant milk powder, and the limitation of detection can reach 1 ?M.

Sun, Yujing; Zhang, Yue; Shi, Yan; Xiao, Xianping; Dai, Haichao; Hu, Jingting; Ni, Pengjuan; Li, Zhuang

2013-10-01

329

Surface-enhanced Raman spectroscopy based on self-assembly structure of silver nanoparticles  

NASA Astrophysics Data System (ADS)

The enhanced Raman spectroscopy (SERS) substrates were obtained using self-assembly Ag nanoparticles on the surface of glass modified with 3-aminopropyltrimethoxysilane (APTES), where the Ag nanoparticles were synthesized by aqueous reduction of AgNO3 with trisodium citrate. The surface morphology of thin films with assembled silver nanoparticles was studied with UV-Vis spectroscopy and SEM. With the probe molecule of Rhodamine 6G, the Raman spectra on self-assembled Ag nanoparticle substrates were detected, which showed a great increase of Raman signals for Rh6. The surface plasmon resonance (SPR) of the assembled silver nanoparticles depended on the distance between the particles, the adsorption of molecules, and the assembly structure. Experimental results indicated that he intensities of the Raman peaks increased concomitantly with the increase in the concentration of Rh 6G. The detection limit of the assembled Ag nanostructures was 10-8M. In this paper, the results further confirmed that the nanoparticles assembled method was an effective method for the increase the signal of SERS.

Li, Xiu; Liu, Wei; Xin, Zhiqing; Li, Yaling; Li, Luhai

2014-07-01

330

Gripe water-mediated green synthesis of silver nanoparticles and their applications in nonlinear optics and surface-enhanced Raman spectroscopy  

NASA Astrophysics Data System (ADS)

In the present study, silver nanoparticles were synthesized from aqueous silver nitrate through a simple, eco-friendly and `green' method using gripe water as reducing as well as stabilizing agent. Control over the dispersity of silver (Ag) nanoparticles was attained by altering the synthesis process. The size and morphology of the particles were perceived using high-resolution transmission electron microscope and the surface plasmon resonance of the prepared nanoparticles was observed by UV-VIS spectrum. Herein, we report the nonlinear optical behavior and surface-enhanced Raman spectroscopy of silver nanoparticles with different particle size and dispersity. The nonlinear optical behavior was studied by single beam Z-scan technique using tunable Ti: Sapphire mode-locked femtosecond laser as source. The nonlinear optical parameters such as the nonlinear refractive index, nonlinear absorption coefficient ? and the third-order nonlinear susceptibility ? 3 of the prepared Ag nanoparticles were obtained for various wavelengths by tuning the wavelength of the laser from 700 to 950 nm. Surface-enhanced Raman spectroscopy (SERS) is an inspiring phenomenon especially in the case of silver nanoparticles. The as-synthesized silver nanoparticles show huge enhancements in the order of 109 in the Raman spectrum of rhodamine 6G dye.

Kirubha, E.; Vishista, K.; Palanisamy, P. K.

2014-11-01

331

Mangifera Indica leaf-assisted biosynthesis of well-dispersed silver nanoparticles  

NASA Astrophysics Data System (ADS)

The use of various parts of plants for the synthesis of nanoparticles is considered as a green technology as it does not involve any harmful chemicals. The present study reports a facile and rapid biosynthesis of well-dispersed silver nanoparticles. The method developed is environmentally friendly and allows the reduction to be accelerated by changing the temperature and pH of the reaction mixture consisting of aqueous AgNO 3 and Mangifera Indica leaf extract. At a pH of 8, the colloid consists of well-dispersed triangular, hexagonal and nearly spherical nanoparticles having size ˜20 nm. The UV-vis spectrum of silver nanoparticles gave surface plasmon resonance (SPR) at 439 nm. The synthesized nanocrystals were characterized using transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Water soluble organics present in the leaf are responsible for the reduction of silver ions. This green method provides faster synthesis comparable to chemical methods and can be used in areas such as cosmetics, foods and medical applications.

Philip, Daizy

2011-01-01

332

Extracellular biosynthesis of silver nanoparticles: effects of shape-directing cetyltrimethylammonium bromide, pH, sunlight and additives.  

PubMed

The work reported in this paper describes the preparation, morphology, stability and sensitivity of Ag-nanoparticles towards sunlight using Allium sativum, garlic extract for the first time. The synthesized silver particles show an intense surface plasmon resonance band in the visible region at 410 nm. The position of the wavelength maxima, blue and red shift, strongly depends on the sunlight and pH. TEM analysis revealed the presence of spherical, different size (from 5.0 to 30 nm) and garlic constituents bio-conjugated, stabilized and/or layered silver nanoparticles. The concentrations of garlic extract, cetyltrimethylammonium bromide, Ag(+) ions and reaction time play vital roles for nucleus formation and the growth processes. Sulfur-containing biomolecules of extract, especially cysteine, are responsible for the reduction of Ag(+) ions into metallic Ag(0). The agglomeration number of the silver nanoparticles (N Ag) and the average number of free electrons per particle (n fe) are calculated and discussed. PMID:24096857

Hussain, Shokit; Akrema; Rahisuddin; Khan, Zaheer

2014-05-01

333

Modelling small gold and silver nanoparticles with electronic structure methods  

Microsoft Academic Search

Electronic structure methods, especially density functional theory (DFT) and time-dependent DFT, have found significant applications in understanding the structure and properties of nanoparticles. In this review, recent studies of the geometric and electronic structure, optical absorption, circular dichroism, growth mechanisms, ligand exchange mechanisms and other properties of thiolate-protected and phosphine-protected gold and silver nanoparticles are discussed in relation to our

Christine M. Aikens

2012-01-01

334

Arabinoxylan-mediated synthesis of gold and silver nanoparticles having exceptional high stability.  

PubMed

A green synthesis of highly stable gold and silver nanoparticles (NPs) using arabinoxylan (AX) from ispaghula (Plantago ovata) seed husk is being reported. The NPs were synthesized by stirring a mixture of AX and HAuCl(4)·H(2)O or AgNO(3), separately, below 100 °C for less than an hour, where AX worked as the reducing and the stabilizing agent. The synthesized NPs were characterized by surface plasmon resonance (SPR) spectroscopy, transmission electron microscopy (TEM), atomic force microscopy (AFM), and X-ray diffraction (XRD). The particle size was (silver: 5-20 nm and gold: 8-30 nm) found to be dependent on pH, temperature, reaction time and concentrations of AX and the metal salts used. The NPs were poly-dispersed with a narrow range. They were stable for more than two years time. PMID:23399234

Amin, Muhammad; Iram, Fozia; Iqbal, Mohammad S; Saeed, Muhammad Z; Raza, Mohsin; Alam, Shehzad

2013-02-15

335

Synthesis and Characterization of Silver Nanoparticles and Silver Inks: Review on the Past and Recent Technology Roadmaps  

NASA Astrophysics Data System (ADS)

The synthesis of silver nanoparticles for silver ink formation has attracted broad interest in the electronic part printing and semiconductor chip industry due to the extraordinary electrical and mechanical properties of these materials. The preparation of silver nanoparticles through a physical or chemical reduction process is the most common methodology applied to obtain nanoparticles with the required size, shape and surface morphology. The chemical solution or solvent carrier applied for silver ink formulation must be applied simultaneously with the direct writing technique to produce the desired adherence, viscosity, and reliable performance. This review paper discusses the details concerning the past and recent advancement of the synthesis and characterization of silver nanoparticles and silver ink formation. A review on the advantages of various sintering techniques, which aim to achieve the electrical and mechanical properties of the required printed structure, is also included. A brief summary concerning the recent challenges and improvement approaches is presented at the end of this review.

Lai, Chin Yung; Cheong, Choke Fei; Mandeep, Jit Singh; Abdullah, Huda Binti; Amin, Nowshad; Lai, Khin Wee

2014-10-01

336

Electrochemical synthesis, characterisation and phytogenic properties of silver nanoparticles  

NASA Astrophysics Data System (ADS)

This work exemplifies a simple and rapid method for the synthesis of silver nanodendrite with a novel electrochemical technique. The antibacterial activity of these silver nanoparticles (Ag NPs) against pathogenic bacteria was investigated along with the routine study of optical and spectral characterisation. The optical properties of the silver nanoparticles were characterised by diffuse reflectance spectroscopy. The optical band gap energy of the electrodeposited Ag NPs was determined from the diffuse reflectance using Kubelka-Munk formula. X-ray diffraction (XRD) studies were carried out to determine the crystalline nature of the silver nanoparticles which confirmed the formation of silver nanocrystals. The XRD pattern revealed that the electrodeposited Ag NPs were in the cubic geometry with dendrite preponderance. The average particle size and the peak broadening were deliberated using Debye-Scherrer equation and lattice strain due to the peak broadening was studied using Williamson-Hall method. Surface morphology of the Ag NPs was characterised by high-resolution scanning electron microscope and the results showed the high degree of aggregation in the particles. The antibacterial activity of the Ag NPs was evaluated and showed unprecedented level antibacterial activity against multidrug resistant strains such as Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumonia and Escherichia coli in combination with Streptomycin.

Singaravelan, R.; Bangaru Sudarsan Alwar, S.

2015-01-01

337

Adsorption mechanisms of RNA mononucleotides on silver nanoparticles  

NASA Astrophysics Data System (ADS)

Surface-enhanced Raman scattering (SERS) of four RNA mononucleotides (AMP, GMP, CMP and UMP) has been studied on the citrate-reduced silver colloid aggregated with sodium sulfate. Concentration dependent spectra in the range of 1 × 10-7-1 × 10-4 mol dm-3 were obtained, assigned and interpreted according to the surface selection rules. For purine mononucleotides, AMP and GMP, adsorption onto the silver nanoparticles through the six-membered ring of the nitrogenous base was suggested. Concentration dependent splitting of the ring breathing band in the spectra of AMP indicated coexistence of two species on the silver surface, which differed in contribution of the adenine N1 atom and the exocyclic NH2 group in binding. Unlike the AMP spectra, the spectra of GMP implied only one mode of adsorption of the molecules onto the silver nanoparticles, taking place through the guanine N1H and Cdbnd O group. Weak SERS spectra of pyrimidine mononucleotides, CMP and UMP, pointed to involvement of carbonyl oxygen in adsorption process, whereby the molecules adopted the position on the nanoparticles with ribose close to the metal surface. Intense bands in the low wavenumber region, associated with stretching of the formed Agsbnd N and/or Agsbnd O bonds, supported chemical binding of the RNA mononucleotides with the silver surface.

Miljani?, Snežana; Dijanoši?, Adriana; Mati?, Ivona

2015-02-01

338

The Speciation Of Silver Nanoparticles In Antimicrobial Fabric Before and After Exposure To A Hypochlorite/Detergent Solution  

EPA Science Inventory

Because of their antibacterial properties, silver nanoparticles are often used in consumer products. To assess environmental and/or human health risks from these nanoparticles, there is a need to identify the chemical transformations that Silver nanoparticles undergo in differen...

339

Toxicity, Bioaccumulation and Biotransformation of Silver Nanoparticles in Marine Organisms  

EPA Science Inventory

The toxicity, bioaccumulation and biotransformation of citrate and polyvinylpyrrolidone (PVP) capped silver nanoparticles (NPs) (AgNP-citrate and AgNP-PVP) and titanium dioxide (TiO2) NPs in marine organisms via marine sediment exposure were investigated. Results from 7-d sedimen...

340

Cytotoxic and genotoxic effects of silver nanoparticles in testicular cells  

Microsoft Academic Search

Serious concerns have been expressed about potential risks of engineered nanoparticles. Regulatory health risk assessment of such particles has become mandatory for the safe use of nanomaterials in consumer products and medicines; including the potential effects on reproduction and fertility, are relevant for this risk evaluation. In this study, we examined effects of silver particles of nano- (20nm) and submicron-

Nana Asare; Christine Instanes; Wiggo J. Sandberg; Magne Refsnes; Per Schwarze; Marcin Kruszewski; Gunnar Brunborg

341

Investigation of the cytotoxicity mechanism of silver nanoparticles in vitro  

Microsoft Academic Search

Nowadays, more and more nanotechnology products and nanomaterials are being applied in our lives. Silver nanoparticles (SNPs) are used in infection prevention and treatment due to their antimicrobial activity. However, as a kind of nanomaterial, the toxicology of SNPs has not been completely studied. The mechanism of cytotoxicity of SNPs in vitro to mouse's fibroblast cells (L929) was investigated in

Lina Wei; Jinglong Tang; Zhixiong Zhang; Yanmei Chen; Gui Zhou; Tingfei Xi

2010-01-01

342

Stirring time effect of silver nanoparticles prepared in glutathione mediated by green method  

PubMed Central

Background This study aims to investigate the influence of different stirring time for synthesis of silver nanoparticles in glutathione (GSH) aqueous solution. The silver nanoparticles (Ag-NPs) were prepared by green synthesis method using GSH as reducing agent and stabilizer, under moderate temperature at different stirring times. Silver nitrate (AgNO3) was taken as the metal precursor while Ag-NPs were prepared in the over reaction time. Results Formation of Ag-NPs was determined by UV–vis spectroscopy where surface plasmon absorption maxima can be observed at 344–354 nm from the UV–vis spectrum. The synthesized nanoparticles were also characterized by X-ray diffraction (XRD). The peaks in the XRD pattern confirmed that the Ag-NPs possessed a face-centered cubic and peaks of contaminated crystalline phases were unable to be located. Transmission electron microscopy (TEM) revealed that Ag-NPs synthesized were in spherical shape. Zeta potential results indicate that the stability of the Ag-NPs is increases at the 72 h stirring time of reaction comparison to GSH. The Fourier transform infrared (FT-IR) spectrum suggested the complexation present between GSH and Ag-NPs. The use of green chemistry reagents, such as peptide, provides green and economic features to this work. Conclusions Ag-NPs were successfully synthesized in GSH aqueous solution under moderate temperature at different stirring times. The study clearly showed that the Ag-NPs synthesized in the long times of stirring, thus, the kinetic of GSH reaction is very slow. TEM results shows that with the increase of stirring times the mean particle size of Ag-NPs become increases. The FT-IR spectrum suggested the complexation present between GSH and Ag-NPs. These suggest that Ag-NPs can be employed as an effective bacteria inhibitor and can be applied in medical field. PMID:24524329

2014-01-01

343

In Vivo Toxicity of Silver Nanoparticles and Silver Ions in Zebrafish (Danio rerio)  

PubMed Central

The influence of water chemistry on characterised polyvinyl pyrrolidone- (PVP-) coated silver nanoparticles (81?nm) was investigated. NaCl solution series of 100–800?mg L?1 lead to initial and temporal increase in nanoparticles size, but agglomeration was limited. pH variation (5–8) had only minor influence on the hydrodynamic particle size. Acute toxicity of nanosivler to zebrafish (Danio rerio) was investigated in a 48-hour static renewal study and compared with the toxicity of silver ions (AgNO3). The nanosilver and silver ion 48-hour median lethal concentration (LC50) values were 84??g L?1 and 25??g L?1, respectively. To investigate exposure-related stress, the fish behaviour was observed visually after 0, 3, 6, 12, 24, 27, 30, and 48 hours of both nanosilver and ionic silver treatments. These observations revealed increased rate of operculum movement and surface respiration after nanosilver exposure, suggesting respiratory toxicity. The present study demonstrates that silver nanoparticles are lethal to zebrafish. PMID:22174711

Bilberg, Katrine; Hovgaard, Mads Bruun; Besenbacher, Flemming; Baatrup, Erik

2012-01-01

344

Extracellular synthesis of mycogenic silver nanoparticles by Cylindrocladium floridanum and its homogeneous catalytic degradation of 4-nitrophenol  

NASA Astrophysics Data System (ADS)

Green synthesis of extracellular mycogenic silver nanoparticles using the fungus, Cylindrocladium floridanum is reported. The synthesized mycogenic silver nanoparticles were characterized using UV-Vis absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. The nanoparticles exhibit fcc structure with Bragg's reflections of (1 1 1), (2 0 0), (2 2 0) and (3 1 1) was evidenced by XRD pattern, high-resolution TEM lattice fringes and circular rings in selected-area electron diffraction (SAED) pattern. The morphology of nanoparticles was roughly spherical in shape with an average size of ca. 25 nm. From FTIR spectrum, it was found that the biomolecules with amide I and II band were involved in the stabilization of nanoparticles. These mycogenic silver nanoparticles exhibited the homogeneous catalytic potential in the reduction of pollutant, 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride, which followed a pseudo-first-order kinetic model. Thus, the synthesis of metal nanoparticles using sustainable microbial approach opens up possibilities in the usage of mycogenic metal nanoparticles as catalysts in various chemical reactions.

Narayanan, Kannan Badri; Park, Hyun Ho; Sakthivel, Natarajan

2013-12-01

345

Extracellular synthesis of mycogenic silver nanoparticles by Cylindrocladium floridanum and its homogeneous catalytic degradation of 4-nitrophenol.  

PubMed

Green synthesis of extracellular mycogenic silver nanoparticles using the fungus, Cylindrocladium floridanum is reported. The synthesized mycogenic silver nanoparticles were characterized using UV-Vis absorption spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. The nanoparticles exhibit fcc structure with Bragg's reflections of (111), (200), (220) and (311) was evidenced by XRD pattern, high-resolution TEM lattice fringes and circular rings in selected-area electron diffraction (SAED) pattern. The morphology of nanoparticles was roughly spherical in shape with an average size of ca. 25 nm. From FTIR spectrum, it was found that the biomolecules with amide I and II band were involved in the stabilization of nanoparticles. These mycogenic silver nanoparticles exhibited the homogeneous catalytic potential in the reduction of pollutant, 4-nitrophenol (4-NP) to 4-aminophenol (4-AP) using sodium borohydride, which followed a pseudo-first-order kinetic model. Thus, the synthesis of metal nanoparticles using sustainable microbial approach opens up possibilities in the usage of mycogenic metal nanoparticles as catalysts in various chemical reactions. PMID:23973598

Narayanan, Kannan Badri; Park, Hyun Ho; Sakthivel, Natarajan

2013-12-01

346

Green synthesis and characterization of silver nanoparticle using Aloe barbadensis  

NASA Astrophysics Data System (ADS)

Green synthesis of silver nanoparticles was achieved by simple visible light irradiation using aloe barbadensis leaf extract as reducing agent. UV-Vis spectroscopic analysis was used for confirmation of the successful formation of nanoparticles. Investigated the effect of light irradiation time on the light absorption of the nanoparticles. It is observed that upto 25 minutes of light irradiation, the absorption is linearly increasing with time and after that it becomes saturated. Finally, theoretically fitted the time-absorption graph and modeled a relation between them with the help of simulation software.

Thappily, Praveen; Shiju, K.

2014-10-01

347

Synthesis of silver nanoparticles using Solanum trilobatum fruits extract and its antibacterial, cytotoxic activity against human breast cancer cell line MCF 7.  

PubMed

In the present study, we have synthesized silver nanoparticles by a simple and eco-friendly method using unripe fruits of Solanum trilobatum. The aqueous silver ions when exposed to unripe fruits extract were reduced and stabilized over long time resulting in biosynthesis of surface functionalized silver nanoparticles. The bio-reduced silver nanoparticles were characterized by UV-visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive spectroscopy (EDX) and X-ray diffraction (XRD). These biologically synthesized silver nanoparticles were tested for its antibacterial activity against few human pathogenic bacteria including Gram-positive (Streptococcus mutans, Enterococcus faecalis) and Gram-negative (Escherichia coli, Klebsiella pneumoniae) bacteria. In addition, we also demonstrated anticancer activity of these nanoparticles in vitro against human breast cancer cell line (MCF 7) using MTT, nuclear morphology assay, Western blot and RT-PCR expression. These results taken together show the potential applications of biosynthesized silver nanoparticles using S. trilobatum fruits. PMID:25613692

Ramar, Manikandan; Manikandan, Beulaja; Marimuthu, Prabhu Narayanan; Raman, Thiagarajan; Mahalingam, Anjugam; Subramanian, Palanisamy; Karthick, Saravanan; Munusamy, Arumugam

2015-04-01

348

Mechanistic aspects of biosynthesis of silver nanoparticles by several Fusarium oxysporum strains  

Microsoft Academic Search

Extracellular production of metal nanoparticles by several strains of the fungus Fusarium oxysporum was carried out. It was found that aqueous silver ions when exposed to several Fusarium oxysporum strains are reduced in solution, thereby leading to the formation of silver hydrosol. The silver nanoparticles were in the range of 20–50 nm in dimensions. The reduction of the metal ions

Nelson Durán; Priscyla D Marcato; Oswaldo L Alves; Gabriel IH De Souza; Elisa Esposito

2005-01-01

349

Psychrotrophic yeast Yarrowia lipolytica NCYC 789 mediates the synthesis of antimicrobial silver nanoparticles via cell-associated melanin  

PubMed Central

A psychrotrophic marine strain of the ascomycetous yeast Yarrowia lipolytica (NCYC 789) synthesized silver nanoparticles (AgNPs) in a cell-associated manner. These nanostructures were characterized by UV-Visible spectroscopy and scanning electron microscope-energy dispersive spectrometer (SEM-EDS) analysis. The brown pigment (melanin) involved in metal-interactions was obtained from the cells. This extracted pigment also mediated the synthesis of silver nanoparticles that were characterized by a variety of analytical techniques. The melanin-derived nanoparticles displayed antibiofilm activity. This paper thus reports the synthesis of AgNPs by the biotechnologically important yeast Y. lipolytica; proposes a possible mechanism involved in the synthetic process and describes the use of the bio-inspired nanoparticles as antibiofilm agents. PMID:23758863

2013-01-01

350

Silver-Based Crystalline Nanoparticles, Microbially Fabricated  

Microsoft Academic Search

One mechanism of silver resistance in microorganisms is accumulation of the metal ions in the cell. Here, we report on the phenomenon of biosynthesis of silver-based single crystals with well-defined compositions and shapes, such as equilateral triangles and hexagons, in Pseudomonas stutzeri AG259. The crystals were up to 200 nm in size and were often located at the cell poles.

Tanja Klaus; Ralph Joerger; Eva Olsson; Claes-Goran Granqvist

1999-01-01

351

Optical absorption properties of dispersed gold and silver alloy nanoparticles.  

PubMed

The oldest topic in nanoscience is the size-dependent optical properties of gold and silver colloids or nanoparticles, first investigated scientifically by Michael Faraday in 1857. In the modern era, advances in both synthesis and characterization have resulted in new insights into the size-dependent absorbance of Au and Ag nanoparticles with sizes below the classical limit for Mie theory. In this paper we discuss the synthesis and properties of core/shell and nanoalloy particles of Au and Ag, compare them to particles of pure gold and silver, and discuss how alloying affects nanoparticle chemical stability. We show that composition, size, and nanostructure (e.g., core/shell vs quasi-random nanoalloy) can all be employed to adjust the optical absorbance properties. The type of nanostructure--core/shell vs alloy--is reflected in their optical absorbance features. PMID:19708105

Wilcoxon, Jess

2009-03-01

352

Completely green synthesis of dextrose reduced silver nanoparticles, its antimicrobial and sensing properties.  

PubMed

We herein report the green synthesis of highly monodispersed, water soluble, stable and smaller sized dextrose reduced gelatin capped-silver nanoparticles (Ag-NPs) via an eco-friendly, completely green method. The synthesis involves the use of silver nitrate, gelatin, dextrose and water as the silver precursor, stabilizing agent, reducing agent and solvent respectively. By varying the reaction time, the temporal evolution of the growth, optical, antimicrobial and sensing properties of the as-synthesised Ag-NPs were investigated. The nanoparticles were characterized using UV-vis absorption spectroscopy, Fourier transform infra-red spectroscopy (FT-IR), X-ray diffraction (XRD), transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HR-TEM). The absorption maxima of the as-synthesized materials at different reaction time showed characteristic silver surface plasmon resonance (SPR) peak. The as-synthesised Ag-NPs show better antibacterial efficacy than the antibiotics; ciproflaxin and imipenem against Pseudomonas aeruginosa with minimum inhibition concentration (MIC) of 6 ?g/mL, and better efficacy than imipenem against Escherichia coli with MIC of 10 ?g/mL. The minimum bactericidal concentration (MBC) of the as-synthesised Ag-NPs is 12.5 ?g/mL. The sensitivity of the dextrose reduced gelatin-capped Ag-NPs towards hydrogen peroxide indicated that the sensor has a very good sensitivity and a linear response over wide concentration range of 10(-1)-10(-6)M H2O2. PMID:24721103

Mohan, Sneha; Oluwafemi, Oluwatobi S; George, Soney C; Jayachandran, V P; Lewu, Francis B; Songca, Sandile P; Kalarikkal, Nandakumar; Thomas, Sabu

2014-06-15

353

A physiologically based pharmacokinetic model for ionic silver and silver nanoparticles.  

PubMed

Silver is a strong antibiotic that is increasingly incorporated into consumer products as a bulk, salt, or nanosilver, thus potentially causing side-effects related to human exposure. However, the fate and behavior of (nano)silver in the human body is presently not well understood. In order to aggregate the existing experimental information, a physiologically based pharmacokinetic model (PBPK) was developed in this study for ionic silver and nanosilver. The structure of the model was established on the basis of toxicokinetic data from intravenous studies. The number of calibrated parameters was minimized in order to enhance the predictive capability of the model. We validated the model structure for both silver forms by reproducing exposure conditions (dermal, oral, and inhalation) of in vivo experiments and comparing simulated and experimentally assessed organ concentrations. Therefore, the percutaneous, intestinal, or pulmonary absorption fraction was estimated based on the blood silver concentration of the respective experimental data set. In all of the cases examined, the model could successfully predict the biodistribution of ionic silver and 15-150 nm silver nanoparticles, which were not coated with substances designed to prolong the circulatory time (eg, polyethylene glycol). Furthermore, the results of our model indicate that: (1) within the application domain of our model, the particle size and coating had a minor influence on the biodistribution; (2) in vivo, it is more likely that silver nanoparticles are directly stored as insoluble salt particles than dissolve into Ag?; and (3) compartments of the mononuclear phagocytic system play a minor role in exposure levels that are relevant for human consumers. We also give an example of how the model can be used in exposure and risk assessments based on five different exposure scenarios, namely dietary intake, use of three separate consumer products, and occupational exposure. PMID:24039420

Bachler, Gerald; von Goetz, Natalie; Hungerbühler, Konrad

2013-01-01

354

A physiologically based pharmacokinetic model for ionic silver and silver nanoparticles  

PubMed Central

Silver is a strong antibiotic that is increasingly incorporated into consumer products as a bulk, salt, or nanosilver, thus potentially causing side-effects related to human exposure. However, the fate and behavior of (nano)silver in the human body is presently not well understood. In order to aggregate the existing experimental information, a physiologically based pharmacokinetic model (PBPK) was developed in this study for ionic silver and nanosilver. The structure of the model was established on the basis of toxicokinetic data from intravenous studies. The number of calibrated parameters was minimized in order to enhance the predictive capability of the model. We validated the model structure for both silver forms by reproducing exposure conditions (dermal, oral, and inhalation) of in vivo experiments and comparing simulated and experimentally assessed organ concentrations. Therefore, the percutaneous, intestinal, or pulmonary absorption fraction was estimated based on the blood silver concentration of the respective experimental data set. In all of the cases examined, the model could successfully predict the biodistribution of ionic silver and 15–150 nm silver nanoparticles, which were not coated with substances designed to prolong the circulatory time (eg, polyethylene glycol). Furthermore, the results of our model indicate that: (1) within the application domain of our model, the particle size and coating had a minor influence on the biodistribution; (2) in vivo, it is more likely that silver nanoparticles are directly stored as insoluble salt particles than dissolve into Ag+; and (3) compartments of the mononuclear phagocytic system play a minor role in exposure levels that are relevant for human consumers. We also give an example of how the model can be used in exposure and risk assessments based on five different exposure scenarios, namely dietary intake, use of three separate consumer products, and occupational exposure. PMID:24039420

Bachler, Gerald; von Goetz, Natalie; Hungerbühler, Konrad

2013-01-01

355

Comparison of in vitro toxicity of silver ions and silver nanoparticles on human hepatoma cells.  

PubMed

Scientific information on the potential harmful effects of silver nanoparticles (AgNPs) on human health severely lags behind their exponentially growing applications in consumer products. In assessing the toxic risk of AgNP usage, liver, as a detoxifying organ, is particularly important. The aim of this study was to explore the toxicity mechanisms of nano and ionic forms of silver on human hepatoblastoma (HepG2) cells. The results showed that silver ions and citrate-coated AgNPs reduced cell viability in a dose-dependent manner. The IC50 values of silver ions and citrate-coated AgNPs were 0.5 and 50 mg L(-1) , respectively. The LDH leakage and inhibition of albumin synthesis, along with decreased ALT activity, indicated that treatment with either AgNP or Ag ions resulted in membrane damage and reduced the cell function of human liver cells. Evaluation of oxidative stress markers demonstrating depletion of GSH, increased ROS production, and increased SOD activity, indicated that oxidative stress might contribute to the toxicity effects of nano and ionic forms of silver. The observed toxic effect of AgNP on HepG2 cells was substantially weaker than that caused by ionic silver, while the uptake of nano and ionic forms of silver by HepG2 cells was nearly the same. © 2014 Wiley Periodicals, Inc. Environ Toxicol, 2014. PMID:25448069

Vr?ek, Ivana Vinkovi?; Zuntar, Irena; Petlevski, Roberta; Pavi?i?, Ivan; Dutour Sikiri?, Maja; Curlin, Marija; Goessler, Walter

2014-11-28

356

Presence of nanoparticles in wash water from conventional silver and nano-silver textiles.  

PubMed

Questions about how to regulate nanoenhanced products regularly arise as researchers determine possible nanoparticle transformation(s). Focusing concern on the incorporation and subsequent release of nano-Ag in fabrics often overshadows the fact that many "conventional silver" antimicrobials such as ionic silver, AgCl, metallic Ag, and other forms will also form different species of silver. In this study we used a laboratory washing machine to simulate the household laundering of a number of textiles prepared with known conventional Ag or nano-Ag treatments and a commercially available fabric incorporating yarns coated with bulk metallic Ag. Serial filtration allowed for quantification of total Ag released in various size fractions (>0.45 ?m, < 0.45 ?m, <0.1 ?m, and <10 kDa), while characterization of particles with TEM/EDX provided insight on Ag transformation mechanisms. Most conventional Ag additives yielded more total Ag and more nanoparticulate-sized Ag in the washing liquid than fabrics that used nano-Ag treatments. Incorporating nano-silver into the fiber (as opposed to surface treatments) yielded less total Ag during fabric washing. A variety of metallic Ag, AgCl, and Ag/S particles were observed in washing solution by TEM/EDX to various extents depending on the initial Ag speciation in the fabrics. Very similar particles were also observed when dissolved ionic Ag was added directly into the washing liquid. On the basis of the present study, we can state that all silver-treated textiles, regardless of whether the treatment is "conventional" or "nano", can be a source of silver nanoparticles in washing solution when laundering fabrics. Indeed, in this study we observed that textiles treated with "conventional" silver have equal or greater propensity to form nano-silver particles during washing conditions than those treated with "nano"-silver. This fact needs to be strongly considered when addressing the risks of nano-silver and emphasizes that regulatory assessment of nano-silver warrants a similar approach to conventional silver. PMID:24941455

Mitrano, Denise M; Rimmele, Elisa; Wichser, Adrian; Erni, Rolf; Height, Murray; Nowack, Bernd

2014-07-22

357

Biosynthesis, characterization and antimicrobial activity of silver nanoparticles by Streptomyces sp. SS2.  

PubMed

In the present study the microbial biosynthesis of silver nanoparticles (AgNPs) by secondary metabolites of Streptomyces sp. SS2 in an eco-friendly approach has been reported. The Streptomyces sp. SS2 was isolated from the soil sediment of Similipal Biosphere Reserve. The identification of this strain was determined by phenotypical characteristics (morphological and biochemical) and molecular characterization method using 16 s rDNA sequencing. The morphological study was also done by high-resolution scanning electron microscopy. The preliminary characterization of biosynthesized silver nanoparticle was carried out using UV-Vis spectrum analysis, which showed an absorption peak at 420 nm corresponding to plasmon absorption of silver. The average size and charge (zeta potential) of the particles were found to be 67.95 ± 18.52 nm and -17.7 ± 5.30 mV, respectively. The functional groups were identified by FTIR studies and their morphology (round and spherical shape) was determined by scanning electron microscopy. The synthesized AgNPs exhibited excellent antibacterial activity against Escherichia coli (MTCC 1089), Bacillus subtilis (MTCC 7164), Staphylococcus epidermis (MTCC 3615), Vibrio cholerae (MTCC 3904) and Staphylococcus aureus (MTCC 1144). These biotechnological approaches of synthesis of nanoparticles can direct a new path in biomaterial sciences and enrich biomedical applications. PMID:24842223

Mohanta, Yugal Kishore; Behera, Sujit Kumar

2014-11-01

358

Measurement of the giant magnetoresistance effect in cobalt-silver magnetic nanostructures: nanoparticles  

NASA Astrophysics Data System (ADS)

Cobalt-silver (Co-Ag) core-shell nanoparticles with different silver thicknesses were prepared by the microemulsion method in a two-step reduction process. Transmission electron microscopy (TEM) characterization revealed the almost monodispersity and nanometric size (in the range 3-5 nm depending on the shell thickness) of the synthesized nanoparticles. However, it was the use of high-resolution TEM that revealed the correct core-shell formation of the nanometric material. The selected area electron diffraction pattern indicated the fcc (face-centered cubic) and hcp (hexagonal close packed) nature for silver and cobalt, respectively. Cyclic voltammetry also allowed the correct core-shell formation to be assured. The magnetic properties revealed the presence of both superparamagnetic and ferromagnetic contributions. Because of the lack of methodology, it was necessary to develop a method to measure the magnetotransport properties of the prepared nanoparticles. The strategy which followed was successful as it was possible to measure these properties: giant magnetoresistance values of 0.1% at room temperature were obtained. The numerical analysis of magnetic and magnetoresistance data indicated the presence of superparamagnetic particles showing interaction among the magnetic moments.

Garcia-Torres, Jose; Vallés, Elisa; Gómez, Elvira

2012-10-01

359

Measurement of the giant magnetoresistance effect in cobalt-silver magnetic nanostructures: nanoparticles.  

PubMed

Cobalt-silver (Co-Ag) core-shell nanoparticles with different silver thicknesses were prepared by the microemulsion method in a two-step reduction process. Transmission electron microscopy (TEM) characterization revealed the almost monodispersity and nanometric size (in the range 3-5 nm depending on the shell thickness) of the synthesized nanoparticles. However, it was the use of high-resolution TEM that revealed the correct core-shell formation of the nanometric material. The selected area electron diffraction pattern indicated the fcc (face-centered cubic) and hcp (hexagonal close packed) nature for silver and cobalt, respectively. Cyclic voltammetry also allowed the correct core-shell formation to be assured. The magnetic properties revealed the presence of both superparamagnetic and ferromagnetic contributions. Because of the lack of methodology, it was necessary to develop a method to measure the magnetotransport properties of the prepared nanoparticles. The strategy which followed was successful as it was possible to measure these properties: giant magnetoresistance values of 0.1% at room temperature were obtained. The numerical analysis of magnetic and magnetoresistance data indicated the presence of superparamagnetic particles showing interaction among the magnetic moments. PMID:22990131

Garcia-Torres, Jose; Vallés, Elisa; Gómez, Elvira

2012-10-12

360

Consequence of silver nanoparticles embedment on the carrier mobility and space charge limited conduction in doped polyaniline  

NASA Astrophysics Data System (ADS)

The present study depicts a one-pot strategy to fabricate silver-polyaniline hybrid nanocomposites with superior and tunable electrical properties, supported by structural characterizations and detail analysis of their temperature dependent current density (J)-voltage (V) characteristics. TEM micrographs clearly reveal that the nanocomposites synthesized by this one-pot strategy contain higher dispersion of sliver nanoparticle within the polyaniline matrix with respect to that obtained from the embedment of externally pre-synthesized silver nanoparticles. The results obtained from the analysis of J-V characteristics indicate the prevalence of trapped charge-limited conduction mechanism in doped polyaniline and its nanocomposites. For the nanocomposites obtained from one-pot strategy, a transition of charge transport mechanism from deep exponential trap limited to shallow traps limited conduction has been occurred due to higher dispersion of silver nanoparticles within the polyaniline matrix. Such distinct variation of charge conduction is absent in the nanocomposites obtained from the embedment of externally pre-synthesized silver nanoparticles. A direct evaluation of carrier mobility as a function of electric field and temperature illustrates that the incorporation of only ?13 to 18 wt% of silver nanoparticles within the polyaniline matrix enhances the carrier mobility in a large extent by reducing the concentration of traps within the polymer matrix. The calculated mobility is consistent with the Poole-Frenkel form for the electrical field up to a certain temperature range. The nonlinear low temperature dependency of mobility of all the nanostructured samples has been explained by Mott variable range hopping conduction mechanisms. Qualitative estimation of various disorder parameters such as optimal hopping distance, localization lengths etc., would help us to outspread the strategies for the fabrication of new organic semiconducting nano-structured devices.

Biswas, Swarup; Dutta, Bula; Bhattacharya, Subhratanu

2014-02-01

361

Dendrigraft polymer-based synthesis of silver nanoparticles showing bright blue fluorescence  

SciTech Connect

A novel method is reported here for the synthesis of optically clear and stable colloidal solutions of silver nanoparticles. According to size they show different colours depending upon their plasmonic absorption frequencies. The materials have been synthesized at room temperature by chemical reduction of silver ions (silver nitrate) coordinated with dendrigraft polymer, polyethyleneimine (PEI) using formaldehyde in aqueous medium. UV-vis absorption and transmission electron microscopy (TEM) studies show single-band absorption with peak maximum at 354 nm for {approx}3 nm sized particles, whereas a side band at {approx}400 nm was observed when the particle size increased to {approx}20 nm. Highly narrow particle size distribution was observed in case of samples having {approx}3 nm size silver particles and also the process of reduction could be completed within minutes. More interestingly, the 3-nm sized particles showed strong blue (474 nm) fluorescence under UV excitation. Thin films of all synthesized samples were prepared on silica substrate by fine spray coating technique.

Manoth, M. [Material Development Group, Defence Laboratory, Jodhpur 342011 (India); Manzoor, K. [Centre for Nanoscience, Amrita Institute of Medical Sciences, Cochin (India); Patra, M.K. [Material Development Group, Defence Laboratory, Jodhpur 342011 (India); Pandey, P. [Defence Research Development Establishment, Gwalior (India); Vadera, S.R. [Material Development Group, Defence Laboratory, Jodhpur 342011 (India); Kumar, N. [Material Development Group, Defence Laboratory, Jodhpur 342011 (India)], E-mail: nkjainjd@yahoo.com

2009-03-05

362

Fabrication of silver nanoparticles doped in the zeolite framework and antibacterial activity  

PubMed Central

Using the chemical reduction method, silver nanoparticles (Ag NPs) were effectively synthesized into the zeolite framework in the absence of any heat treatment. Zeolite, silver nitrate, and sodium borohydride were used as an inorganic solid support, a silver precursor, and a chemical reduction agent, respectively. Silver ions were introduced into the porous zeolite lattice by an ion-exchange path. After the reduction process, Ag NPs formed in the zeolite framework, with a mean diameter of about 2.12–3.11 nm. The most favorable experimental condition for the synthesis of Ag/zeolite nanocomposites (NCs) is described in terms of the initial concentration of AgNO3. The Ag/zeolite NCs were characterized by ultraviolet-visible spectroscopy, powder X-ray diffraction, transmission electron microscopy, scanning electron microscopy, energy dispersive X-ray fluorescence, and Fourier transform infrared. The results show that Ag NPs form a spherical shape with uniform homogeneity in the particle size. The antibacterial activity of Ag NPs in zeolites was investigated against Gram-negative bacteria (ie, Escherichia coli and Shigella dysentriae) and Gram-positive bacteria (ie, Staphylococcus aureus and methicillin-resistant Staphylococcus aureus) by disk diffusion method using Mueller–Hinton agar at different sizes of Ag NPs. All of the synthesized Ag/zeolite NCs were found to have antibacterial activity. These results show that Ag NPs in the zeolite framework can be useful in different biological research and biomedical applications. PMID:21383858

Shameli, Kamyar; Ahmad, Mansor Bin; Zargar, Mohsen; Yunus, Wan Md Zin Wan; Ibrahim, Nor Azowa

2011-01-01

363

Enhanced antibacterial activity of silver/polyrhodanine-composite-decorated silica nanoparticles.  

PubMed

This work describes the synthesis of silver/polyrhodanine-composite-decorated silica nanoparticles and their antibacterial activity. Polymerization of polyrhodanine proceeded preferentially on the surface of the silica nanoparticles where Ag(+) ions were located. In addition, the embedded Ag(+) ions were reduced to form metallic Ag nanoparticles; consequently, silver/polyrhodanine-composite nanoparticles (approximately 7 nm in diameter) were formed on the surface of the silica nanoparticles. The resulting nanostructure was investigated using electron microscopy, Fourier-transform infrared spectroscopy, ultraviolet-visible spectroscopy, and X-ray photoelectron spectroscopy. The silver/polyrhodanine-nanocomposite-decorated silica nanoparticles exhibited excellent antimicrobial activity toward gram-negative Escherichia coli and gram-positive Staphylococcus aureus because of the antibacterial effects of the silver nanoparticles and the polyrhodanine. The silver/polyrhodanine-composite nanoparticles may therefore have potential for use as a long-term antibacterial agent. PMID:24156562

Song, Jooyoung; Kim, Hyunyoung; Jang, Yoonsun; Jang, Jyongsik

2013-11-27

364

Long-term active antimicrobial coatings for surgical sutures based on silver nanoparticles and hyperbranched polylysine.  

PubMed

The goal of this study was to develop a long-term active antimicrobial coating for surgical sutures. To this end, two water-insoluble polymeric nanocontainers based on hyperbranched polylysine (HPL), hydrophobically modified by either using glycidyl hexadecyl ether, or a mixture of stearoyl/palmitoyl chloride, were synthesized. Highly stabilized silver nanoparticles (AgNPs, 2-5?nm in size) were generated by dissolving silver nitrate in the modified HPL solutions in toluene followed by reduction with L-ascorbic acid. Poly(glycolic acid)-based surgical sutures were dip-coated with the two different polymeric silver nanocomposites. The coated sutures showed high efficacies of more than 99.5% reduction of adhesion of living Staphylococcus aureus cells onto the surface compared to the uncoated specimen. Silver release experiments were performed on the HPL-AgNP modified sutures by washing them in phosphate buffered saline for a period of 30?days. These coatings showed a constant release of silver ions over more than 30?days. After this period of washing, the sutures retained their high efficacies against bacterial adhesion. Cytotoxicity tests using L929 mouse fibroblast cells showed that the materials are basically non-cytotoxic. PMID:23574366

Ho, Chau Hon; Odermatt, Erich K; Berndt, Ingo; Tiller, Joerg C

2013-01-01

365

Bioconcentration and distribution of silver nanoparticles in Japanese medaka (Oryzias latipes).  

PubMed

The study of the bioconcentration of silver nanoparticles (AgNPs) is important to fully understand their hazard potential in the aquatic environment. We synthesized AgNPs radiolabeled with silver isotopes ((110m)Ag) to quantify the bioconcentration of AgNPs coated with citrate (AgNPs-CIT) and polyvinylpyrrolidone (AgNPs-PVP) in Japanese medaka, and to investigate the biodistribution of silver in organs, which were compared with (110m)AgNO3. BCF values were determined to be 39.8±7.4, 42.5±5.1 and 116.4±6.1Lkg(-1) for AgNPs-CIT, AgNPs-PVP and AgNO3, respectively. The release of more silver ions in AgNPs-PVP contributed to a different kinetic uptake pattern with AgNPs-CIT, which was similar to that of AgNO3. Bioconcentrated AgNPs in medaka were not observed to be eliminated, independent of surface coating differences, similarly to AgNO3. There was no difference in biodistribution in each organ before and after depuration in two types of AgNPs and AgNO3, all of which were mainly concentrated in the liver. This study quantified the bioconcentration and distribution of AgNPs and AgNO3 more precisely by utilizing a silver isotope, which is helpful in monitoring the toxicity of AgNPs to Japanese medaka. PMID:24457612

Jung, Youn-Joo; Kim, Ki-Tae; Kim, Jun Y; Yang, Song-Yi; Lee, Byeong-Gweon; Kim, Sang D

2014-02-28

366

PEGylated silver doped zinc oxide nanoparticles as novel photosensitizers for photodynamic therapy against Leishmania.  

PubMed

We describe daylight responsive silver (Ag) doped semiconductor nanoparticles of zinc oxide (DSNs) for photodynamic therapy (PDT) against Leishmania. The developed materials were characterized by X-ray diffraction analysis (XRD), Rutherford backscattering (RBS), diffused reflectance spectroscopy (DRS), and band-gap analysis. The Ag doped semiconductor nanoparticles of zinc oxide were PEGylated to enhance their biocompatibility. The DSNs demonstrated effective daylight response in the PDT of Leishmania protozoans, through the generation of reactive oxygen species (ROS) with a quantum yield of 0.13 by nondoped zinc oxide nanoparticles (NDSN) whereas 0.28 by DSNs. None of the nanoparticles have shown any antileishmanial activity in dark, confirming that only ROS produced in the daylight were involved in the killing of leishmanial cells. Furthermore, the synthesized nanoparticles were found biocompatible. Using reactive oxygen species scavengers, cell death was attributable mainly to 77-83% singlet oxygen and 18-27% hydroxyl radical. The nanoparticles caused permeability of the cell membrane, leading to the death of parasites. Further, the uptake of nanoparticles by Leishmania cells was confirmed by inductively coupled plasma atomic emission spectroscopy (ICP-AES). We believe that these DSNs are widely applicable for the PDT of leishmaniasis, cancers, and other infections due to daylight response. PMID:25266330

Nadhman, Akhtar; Nazir, Samina; Ihsanullah Khan, Malik; Arooj, Syeda; Bakhtiar, Muhammad; Shahnaz, Gul; Yasinzai, Masoom

2014-12-01

367

Antibacterial potential of biosynthesised silver nanoparticles using Avicennia marina mangrove plant  

NASA Astrophysics Data System (ADS)

The present study was aimed to identify the antibacterial potential of biosynthesised silver nanoparticles using different plant parts (leaves, bark and root) of Avicenna marina mangrove plant. Of the selected three different parts, the leaf extract showed the maximum synthesis of silver nanoparticles. The in vitro antibacterial assay (100 ?g disk-1 concentration) showed the results of maximum zone of inhibition with the E. coli (18.40 ± 0.97 mm), and minimum (10.87 ± 1.33 mm) zone of inhibition with S. aureus but the concentrations of MIC and MBC values ranged between 6.25 and 50.0 ?g ml-1 between the selected bacterial strains. The FTIR results of most potent leaf extract-synthesized silver nanoparticles showed the prominent peaks (620.967; 1,061.02; 1,116.58; 1,187.94; 1,280.50; 1,353.79; 1,384.64; 1,598.50; 1,629.56; 2,854.14 and 2,927.42) in different ranges. Further, the results of XRD analysis showed the 2 ? intense values (38.11 and 70.57) within the ranges of Bragg's reflection. In addition, the AFM analysis showed the results of particle sizes (71-110 nm), particle roughness (11.8 nm), maximum height of the particle roughness (111.8 nm), and average maximum height of the particle roughness (57.5 nm). It can be concluded from the present findings that, the biosynthesis of silver nanoparticles from the leaf extract of A. marina can be used as potential antibacterial agents.

Gnanadesigan, M.; Anand, M.; Ravikumar, S.; Maruthupandy, M.; Syed Ali, M.; Vijayakumar, V.; Kumaraguru, A. K.

2012-06-01

368

Preparation of silver nanofluid by the submerged arc nanoparticle synthesis system (SANSS)  

Microsoft Academic Search

The purpose of this study is fabrication and characterization of silver nanofluid by the submerged arc nanoparticle synthesis system (SANSS). The silver metal electrodes under the electrical discharge will melt and evaporate rapidly and condense to form the nanoparticles in the lower temperature dielectric liquid and produce the suspended nanoparticle. The results showed that the spherical nanosilver particle formed in

Chih-Hung Lo; Tsing-Tshih Tsung; Hong-Ming Lin

2007-01-01

369

Biosynthesis of silver nanoparticles using Plectranthus amboinicus leaf extract and its antimicrobial activity.  

PubMed

This study reports the simple green synthesis method for the preparation of silver nanoparticles (Ag NPs) using Plectranthus amboinicus leaf extract. The pathway of nanoparticles formation is by means of reduction of AgNO3 by leaf extract, which acts as both reducing and capping agents. Synthesized Ag NPs were subjected to different characterizations for studying the structural, chemical, morphological, optical and antimicrobial properties. The bright circular fringes in SAED pattern and diffraction peaks in XRD profile reveals high crystalline nature of biosynthesized Ag NPs. Morphological studies shows the formation of nearly spherical nanoparticles. FTIR spectrum confirms the existence of various functional groups of biomolecules capping the nanoparticles. UV-visible spectrum displays single SPR band at 428 nm indicating the absence of anisotropic particles. The synthesized Ag NPs exhibited better antimicrobial property towards gram negative Escherichia coli and towards tested Penicillium spp. than other tested microorganisms using disc diffusion method. Finally it has proven that the synthesized bio-inspired Ag NPs have potent antimicrobial effect. PMID:24674916

Ajitha, B; Ashok Kumar Reddy, Y; Sreedhara Reddy, P

2014-07-15

370

ARSENIC REMOVAL USING SOL-GEL SYNTHESIZED TITANIUM DIOXIDE NANOPARTICLES  

EPA Science Inventory

In this study, the effectiveness of TiO2 nanoparticles in arsenic adsorption was examined. TiO2 particles (LS) were synthesized via sol-gel techniques and characterized for their crystallinity, surface area and pore volume. Batch adsorption studies were perf...

371

Attenuation of allergic airway inflammation and hyperresponsiveness in a murine model of asthma by silver nanoparticles  

PubMed Central

The use of silver in the past demonstrated the certain antimicrobial activity, though this has been replaced by other treatments. However, nanotechnology has provided a way of producing pure silver nanoparticles, and it shows cytoprotective activities and possible pro-healing properties. But, the mechanism of silver nanoparticles remains unknown. This study was aimed to investigate the effects of silver nanoparticles on bronchial inflammation and hyperresponsiveness. We used ovalbumin (OVA)-inhaled female C57BL/6 mice to evaluate the roles of silver nanoparticles and the related molecular mechanisms in allergic airway disease. In this study with an OVA-induced murine model of allergic airway disease, we found that the increased inflammatory cells, airway hyperresponsiveness, increased levels of IL-4, IL-5, and IL-13, and the increased NF-?B levels in lungs after OVA inhalation were significantly reduced by the administration of silver nanoparticles. In addition, we have also found that the increased intracellular reactive oxygen species (ROS) levels in bronchoalveolar lavage fluid after OVA inhalation were decreased by the administration of silver nanoparticles. These results indicate that silver nanoparticles may attenuate antigen-induced airway inflammation and hyperresponsiveness. And antioxidant effect of silver nanoparticles could be one of the molecular bases in the murine model of asthma. These findings may provide a potential molecular mechanism of silver nanoparticles in preventing or treating asthma. PMID:20957173

Park, Hee Sun; Kim, Keun Hwa; Jang, Sunhyae; Park, Ji Won; Cha, Hye Rim; Lee, Jeong Eun; Kim, Ju Ock; Kim, Sun Young; Lee, Choong Sik; Kim, Joo Pyung; Jung, Sung Soo

2010-01-01

372

Synthesis, Characterization and Manipulation of Creighton Silver Nanoparticles for Future Cytotoxicity Studies.  

E-print Network

??Nowadays, 24% of the nanomaterial-based consumer products contain silver nanoparticles (AgNPs) and exploit the well-known antimicrobial properties of silver. Although AgNPs have a wide range… (more)

Paluri, Sesha Lakshmi Arathi

2011-01-01

373

Extracellular Production of Silver Nanoparticles by Using Three Common Species of Dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis  

PubMed Central

Background: To develop a new green approach for biosynthesis of silver nanoparticles, myconanotechnology has been represented as a novel field of study in nanotechnology. In this study, we have reported the extracellular synthesis of highly stable silver nanoparticles using three species of dermatophytes: Trichophyton rubrum, Trichophyton mentagrophytes and Microsporum canis. Methods: Clinical strains of these species were grown in a liquid medium containing mineral salt and incubated at 25°C for 5-7 days. The cell-free filtrate of each culture was obtained and subjected to synthesize silver nanoparticles in the presence of 1 mM AgNO3. Results: The reduction of Ag+ ions in metal nanoparticles was investigated virtually by tracing the solution color which was switched into reddish-light brown after 72 h. For T. mentagrophytes, a UV-visible spectra demonstrating a strong, quite narrow peak located between 422 and 425 nm was obtained. For M. canis, a fairly wide peak centering at 441 nm and for T. rubrum, a weak spectrum to decipher were observed. According to transmission electron microscopy (TEM) results, fairly uniform, spherical, and small in size with almost less than 50 nm particles were forms in case of T. mentagrophytes. For the other two species, TEM images showed existence of small spherical nanosilvers but not as small as nanoparticles synthesized by T. mentagrophytes. Conclusion: We observed that species belong to a single genus of the fungi have variable ability to synthesize silver nanoparticles extracellulary with different efficiency. Furthermore, the extracellular synthesis may make the process simpler and easier for following processes. PMID:22562033

Moazeni, Maryam; Rashidi, Niloofar; Shahverdi, Ahmad R.; Noorbakhsh, Fatemeh; Rezaie, Sassan

2012-01-01

374

TOXICITY OF SILVER NANOPARTICLES TO DAPHNIA MAGNA  

EPA Science Inventory

Relatively little is known regarding toxicity of nanoparticles in the environment. It is widely assumed that the toxicity of nanoparticles will be less than that of their metallic ions. Also the effect of organics on metal toxicity is well established. Presented here are the resu...

375

Inoculation of silicon nanoparticles with silver atoms  

E-print Network

-sputter inert-gas aggregation has emerged as one of the most prevalent and flexible techniques because chemistries of Si and Ag28 . Nanoparticles were produced using a modified inert-gas aggregated magnetron condense, nucleate and diffuse into the liquid Si nanoparticles in a process that we term ``inoculation

Nordlund, Kai

376

Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro  

NASA Astrophysics Data System (ADS)

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

2010-12-01

377

Silver and Gold Nanoparticles Alter Cathepsin Activity In vitro  

NASA Astrophysics Data System (ADS)

Nanomaterials are being incorporated into many biological applications for use as therapeutics, sensors, or labels. Silver nanomaterials are being utilized for biological implants and wound dressings as an antiviral material, whereas gold nanomaterials are being used as biological labels or sensors due to their surface properties and biocompatibility. Cytotoxicity data of these materials are becoming more prevalent; however, little research has been performed to understand how the introduction of these materials into cells affects cellular processes. Here, we demonstrate the impact that silver and gold nanoparticles have on cathepsin activity in vitro. Cathepsins are important cellular proteases that are imperative for proper immune system function. We have selected to examine gold and silver nanoparticles due to the increased use of these materials in biological applications. This manuscript depicts how both of these types of nanomaterials affect cathepsin activity, which could impact the host's immune system and its ability to respond to pathogens. Cathepsin B activity decreases in a dose-dependent manner with all nanoparticles tested. Alternatively, the impact of nanoparticles on cathepsin L activity depends greatly on the type and size of the material.

Speshock, Janice L.; Braydich-Stolle, Laura K.; Szymanski, Eric R.; Hussain, Saber M.

2011-12-01

378

Shaped platinum nanoparticles directly synthesized inside mesoporous silica supports.  

PubMed

It is difficult to deposit shape-controlled nanoparticles into a mesoporous framework while preserving the shape. For shaped platinum nanoparticles, which are typically 5-10 nm in size, capillary inclusion by sonication or the formation of a mesoporous framework around the shaped platinum nanoparticles has been attempted, but the nanoparticles aggregated or their shapes were degraded easily. In this work, we directly nucleated platinum on the surface inside a mesoporous silica support and controlled the overgrowth step, producing cubic shaped nanoparticles. Mercaptopropyltrimethoxysilane was used as an anchoring agent causing nucleation at the silica surface, and it also helped to shape the nanoparticles. Platinum nanocubes, which were synthesized with polymeric capping agents separately, were deposited inside the mesoporous silica by sonication, but most of the nanoparticles were clogged at the entrance to the pores, and the surface of the platinum had very few sites that were catalytically active, as evidenced by the small H2 uptake. Unshaped platinum nanoparticles, which were prepared by conventional wet impregnation, showed a similar amount of H2 uptake as the in situ shaped platinum cubes, but the selectivity for pyrrole hydrogenation was poorer towards the production of pyrrolidine. The mesoporosity and the residual thiol groups on the surface of the in situ shaped Pt nanocubes might cause a high selectivity for pyrrolidine. PMID:25177923

Kim, Jiwhan; Bae, Youn-Sang; Lee, Hyunjoo

2014-11-01

379

Tuning the electromagnetic field coupling between nanoporous silver and silver nanoparticles connected by hybridized oligonucleotide  

NASA Astrophysics Data System (ADS)

On monolithic nanoporous silver (NPS), via DNA hybridization, we constructed an NPS/DNA-Cy5/silver nanoparticle (Ag NP) sandwich to investigate its SERS effect. In this sandwich, no chemical enhancement contributes to the SERS signal of Cy5. As compared with NPS, the present substrate exhibits particularly strong electromagnetic (EM) field enhancement. At the same Ag NPs surface loading, the SERS intensity decreases exponentially with increasing the length of double-stranded DNA (dsDNA). A larger pore size of NPS leads to weaker EM enhancement within the sandwich, but the relative intensity is not sensitive to the sizes and it is determined by the length of dsDNA.

Zhao, Yin; Yan, Keqian; Huang, Xirong; Zhang, Zhonghua; Qu, Yinbo

2013-01-01

380

Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies  

NASA Astrophysics Data System (ADS)

Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg2+, Cd2+ and Pb2+ metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology.

Vinod Kumar, V.; Anbarasan, S.; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

2014-08-01

381

Bio-functionalized silver nanoparticles for selective colorimetric sensing of toxic metal ions and antimicrobial studies.  

PubMed

Hibiscus Sabdariffa (Gongura) plant extracts (leaves (HL) and stem (HS)) were used for the first time in the green synthesis of bio-functionalized silver nanoparticles (AgNPs). The bio-functionality of AgNPs has been successfully utilized for selective colorimetric sensing of potentially health and environmentally hazardous Hg(2+), Cd(2+) and Pb(2+) metal ions at ppm level in aqueous solution. Importantly, clearly distinguishable colour for all three metal ions was observed. The influence of extract preparation condition and pH were also explored on the formation of AgNPs. Both selectivity and sensitivity differed for AgNPs synthesized from different parts of the plant. Direct correlation between the stability of green synthesized AgNPs at different pH and its antibacterial effects has been established. The selective colorimetric sensing of toxic metal ions and antimicrobial effect of green synthesized AgNPs demonstrated the multifunctional applications of green nanotechnology. PMID:24717716

Vinod Kumar, V; Anbarasan, S; Christena, Lawrence Rene; SaiSubramanian, Nagarajan; Philip Anthony, Savarimuthu

2014-08-14

382

Silver Nanoparticles Dispersed in Poly(methyl methacrylate) Thin Films: Spectroscopic and Electrical Properties  

NASA Astrophysics Data System (ADS)

Silver nanoparticles of different sizes were prepared following chemical route and using silver nitrate as starting material. The nanoparticles were dispersed in Poly(methyl methacrylate) (PMMA) matrix and thin films were prepared. The PMMA films with dispersed silver nanoparticles were characterized by UV-Vis absorption spectroscopy and FESEM. The electrical measurements were carried out by using surface type cells. The absorption spectra of the films have shown plasmon peaks at different wavelengths with the variation in size of the silver nanoparticles. The film with dispersed silver nanoparticles showing plasmon peak at higher wavelength manifested increasing trend in dark current values with time at room temperature. On the contrary, the decreasing dark current values with time were observed in the case of the film showing plasmon peak at lower wavelength under similar measuring conditions. The photocurrent profile of the PMMA film with dispersed silver nanoparticles as a function of photoexcitation wavelength showed dependence on the position of the plasmon bands.

Majumder, Manisree; Chakraborty, Aloke Kumar; Mallik, Biswanath

2009-06-01

383

Effect of silver nanoparticles on human mesenchymal stem cell differentiation  

PubMed Central

Summary Background: Silver nanoparticles (Ag-NP) are one of the fastest growing products in nano-medicine due to their enhanced antibacterial activity at the nanoscale level. In biomedicine, hundreds of products have been coated with Ag-NP. For example, various medical devices include silver, such as surgical instruments, bone implants and wound dressings. After the degradation of these materials, or depending on the coating technique, silver in nanoparticle or ion form can be released and may come into close contact with tissues and cells. Despite incorporation of Ag-NP as an antibacterial agent in different products, the toxicological and biological effects of silver in the human body after long-term and low-concentration exposure are not well understood. In the current study, we investigated the effects of both ionic and nanoparticulate silver on the differentiation of human mesenchymal stem cells (hMSCs) into adipogenic, osteogenic and chondrogenic lineages and on the secretion of the respective differentiation markers adiponectin, osteocalcin and aggrecan. Results: As shown through laser scanning microscopy, Ag-NP with a size of 80 nm (hydrodynamic diameter) were taken up into hMSCs as nanoparticulate material. After 24 h of incubation, these Ag-NP were mainly found in the endo-lysosomal cell compartment as agglomerated material. Cytotoxicity was observed for differentiated or undifferentiated hMSCs treated with high silver concentrations (?20 µg·mL?1 Ag-NP; ?1.5 µg·mL?1 Ag+ ions) but not with low-concentration treatments (?10 µg·mL?1 Ag-NP; ?1.0 µg·mL?1 Ag+ ions). Subtoxic concentrations of Ag-NP and Ag+ ions impaired the adipogenic and osteogenic differentiation of hMSCs in a concentration-dependent manner, whereas chondrogenic differentiation was unaffected after 21 d of incubation. In contrast to aggrecan, the inhibitory effect of adipogenic and osteogenic differentiation was confirmed by a decrease in the secretion of specific biomarkers, including adiponectin (adipocytes) and osteocalcin (osteoblasts). Conclusion: Aside from the well-studied antibacterial effect of silver, little is known about the influence of nano-silver on cell differentiation processes. Our results demonstrate that ionic or nanoparticulate silver attenuates the adipogenic and osteogenic differentiation of hMSCs even at non-toxic concentrations. Therefore, more studies are needed to investigate the effects of silver species on cells at low concentrations during long-term treatment.

Diendorf, Jörg; Epple, Matthias; Schildhauer, Thomas A; Köller, Manfred

2014-01-01

384

Silver and nanoparticles of silver in wound dressings: a review of efficacy and safety.  

PubMed

Wound infections present a significant clinical challenge, impacting on patient morbidity and mortality, with significant economic implications. Silver-impregnated wound dressings have the potential to reduce both wound bioburden and healing time. The silver ion Ag+ is the active antimicrobial entity; it can interfere with thiol (-SH) groups and provoke the generation of reactive oxygen species (ROS), a major contributor to its antibacterial efficacy. Recently, silver nanoparticles have gained considerable interest in wound bioburden reduction and in anti-inflammation, as they can release Ag+ ions at a greater rate than bulk silver, by virtue of their large surface area. If released from dressings, they also have the potential to cross biological compartments. This review aims to consolidate recent findings as to the efficacy and safety of different formulations of silver used as an antiseptic agent in dressings, summarising the features of silver nanomaterials, with particular attention to the dose-dependencies for biological effects, highlighting the need for information on their uptake and potential biological effects. PMID:22240850

Wilkinson, L J; White, R J; Chipman, J K

2011-11-01

385